There are so many things that have been, I believe, influenced by community feedback- with the delay as you say. Part of it is pretty logical, you can't just turn a ship around instantly, and the other part might be whatever logistical bias or "lets make sure they ACTUALLY want that or... ...m... I don't love that idea... do they actually want that...?..." and they're trying to let the dust setttle before they change a bunch of things.
One other thing, I feel, to add to that vague list of rules I mentioned earlier is that they don't like substantially changing old things if they can help it. I think it's a sense of wasting time in the past for minor gain vs making new content that more accurately fits their playerbase feedback which is a net overall greater amount of content. I mean they do go back and change stuff but I think we've heard Yoshida make a comment on that before, and also you can tell it's not their favorite thing to do (they do it, they just don't do it 24/7).
I don't try and sit and memorize everything they listen to, particularly because of the time shift, but you've got a lot of blue changes that I strongly believe they did the above rules with (like I wish they changed the starting part of blue more, but you can see they did do that a bit but also their newer added spells did a lot to address any feedback that wasn't on the topic of making it unlimited, or making larger changes to the starting skills*, as well as adding a lot of features I saw mentioned including 100% learn rate in groups etc). *Doesn't mean I don't still hope they'll consider it, since I think the pacing of the job could be improved, longevity of some of the skills that seem to exist for like only one carnival event, make them more interesting as well since the job is limited so balance isn't as important, etc.. BUT I feel you can see in multiple phases, including the new skills added, they were directly listening to feedback.
When they were talking about how echo would be less powerful because of their stat changes I and a few others were like "please don't kill the solo potential for old content" and then in like the next live letter they were talking about epic echo which repaired the damage to that system.
When they add new zones to expansions I swear to Thal there is at least one or two that I have seen people request specifically (in theme).
A few that I can think of without stiting too long with a pencil up my nose (don't want to spend too long thinking of it) trying to remember 10+ years of comments, (some will have to be coincidence), are things like:
- Summoner egi/demi thing + progressively more primal-y summoner
- gpose (in 1.0-2.0 beta era I had talked about adding a camera and posing system to capture memories)
- Paladin protective tyrael wings
- multiple UI QoL (like the aethernet map, quest item linking, inventory searching (via cataloging the inventories client side, as they had said it wasn't really possible when people first requested it), transferring and saving UI
- Island Sanctuary like content
- Condense buttons
- Materia changes (long ago)
- group craft projects (which unfortunately appears to have not panned out because people hardly craft together in the FC...)
- Zones (before ShB asking for a hyper vertical zone and Zanarkand like zone, pre-EW hoping for a Zeal like space)
- Race (I had asked for Ronso-like race... lol)
- Freaking grass - during the 1.0-2.0 era, which had multiple patches specifically (at the time many mocked me for but even Yoshida has now said "hmmm, that's killing some of my cutscenes" meanwhile many MMOs have focused on specifically this feature and such a thing covers most of the screen in some spaces, so I think it sounds silly but people were being foolish to think it's irrelevant, though I think my post at the time could have been better worded)
- Locking servers that are too full even against the cash shop and then creating systems to encourage players to balance out other servers (preferred, full worlds, etc)
- Jobs (a lot of suggestions I made to people who said lore impossible to new dark theme jobs had many similarities to reaper added later, including using wraiths to by pass any undead type concerns (like zombies/skeletons)). Not forgetting the fact that the request for a scythe weapon had been going on for a while by others.
- I was in a thread mentioning a unique weapon idea could be pylons that float behind the player and attack (similar enough someone on the forums was like "did I read this somewhere here?")
- Healer job that uses attacking as a way to heal to increase the amount of offense opportunities
- The consistent empowering of beast tribe content and other player builds a space features (like Ishgard reconstruction I believe was a direct larger scale response to players saying "I like making changes to the world")
- Blue mage changes above, from more interesting spells, learn rates, to solo power
- Epic echo
- etc... etc...
I'm 100% sure some of it is coincidence, but there are many like that which are eerily similar with twists on ideas. Like for example for me it was crystal pylons that would float behind the player and could attack / fire off like Fenrir and be used for a Geomancer like job (as the pylons would create field effects), clearly some differences yet at the same time the weapon idea isn't super common so I feel it's not unreasonable to imagine that might have had some impact.
Of course as I said before I could have posted so much that sometimes I get close because I do.. like some sort of Nostradamus lol (make enough comments some of them will come true XD).. for example before GW2 had their very well received mount system I was trying to suggest FFXIV have a far more in-depth mount system rather than them being all different cans of paint. Now WoW is taking major influences from GW2 system and often when people talk about mounts you hear "GW2 is the best one". Highly doubt I had any influence on GW2 from the FFXIV forums, but I think I just had the right idea that movement can be fun even if it initially sounds kind of silly to spend so much time making movement interesting (which is proof to me that sometimes it is likely just coincidence, but too many times coincidence doesn't sound as likely). Of course I'd say GW2's idea was far more refined, but you'd hope so... with their experienced perspective and it being their job you'd hope ideas are more refined.
Heck, when people were talking about the Island by Garlean (with all the lightning) I had suggested it was owned by ancients and looked like Zeal in the past, and the players will go into the past to learn important information but wont change the future. I feel that is weirdly similar to a situation we have in game.. lol. Honestly If I spoke Japanese I'd probably apply and say either I've said enough acceptable things that feedback is taken or alternatively I've a decent track record for parodying actual content changes to the game before they happen so I'm not a terrible fit (I don't think I'd be even a tenth as talented as those who actually have industry experience but that's called learning, but I also don't think I'm far off the mark.. usually.. LONG ago I did have a bad take on the glamour system in which I was against it.. but it's clear to me that for many people glamour is substantial end game and such a system should be a treasured concept...).
I mean long, long, ago they literally said they spend a decent amount of time compiling forum posts and sharing the feedback to the related teams (to which was a question I asked them via another website).
I'm confident I could easily think of 10 or more things that I've personally mentioned that are eerily similar to game results, which again I would say it's imperative that I believe some of them are just coincidence and many are inspirations / influences to the people who might have already had similar thoughts but feel "sounds good now that someone else thinks that's cool too", but when people say "they don't listen" I just have a really hard time believing it. That's just what I've mentioned, I've seen feedback other people have said to which similar things have happened.
They might not do what you want when you want, or occasionally their vision of content is different and someone in the dev side is like "no you listen here, this is better" (like housing probably, but that's also likely a money issue because changing those systems is probably insanely expensive), but I still believe they sincerely take feedback and incorporate it when it makes sense to them.