You know that items from in-game events can be stored in the armoire from the time you get them, right? There's only been a couple pieces they forgot to do but that got fixed rather quickly.
I only remember FFXIV going F2P during 1.0, and it happened twice, the first because the game was so bad, and the second time because they were ending 1.0.
They do know about the space issue. That's partly why belt space is being reallocated to weapons and rings, which is the biggest offenders regarding armoury space.
Now to actually address the topic.
I agree that we need a better glamour system. We do need something like a glamour closet or catalog or whatever you want to call it. We need more glamour plates. Dyes are ridiculous.
You're right that this was built like it was made during ARR, which is sad because it was released during SB.
There major issues they have present that would need to be addressed, and I'd like to note I'm NOT defending their excuses nor can I explain from a technical standpoint, I'm just stating facts here and maybe offering solutions.
From what I understand, one issue is something to the effect of how the game checks everything stored on your character CONSTANTLY to keep everything in sync between the server and your client. This includes what's in your inventory, your armoury, your armoire, orchestrations, minions, mounts, and all that good stuff. That's a lot of stuff it needs to check every so often. And the resistance to adding a closet system for glamours probably has a lot to do with this. It'd have to go through every armor in the game to determine if you've had it or not.
Personally, I think they could revamp the glamour dresser to basically be the call button for that lookup. I think we all expect a little delay when we go to do certain things. Like retainers sometimes take a bit to come out, I assume using the bell is when it calls that retainer out. The armoire should also be the call button for the lookup for it too. There's some things that the game just doesn't really need to look to see if it's attached to your character at all times. Yes, some people might be bothered that they still have to go to their inn to access the glamour dresser, but I think a lot of us would even accept this minor inconvenience. I know in WoW, you can do it anywhere, but WoW isn't tied to antiquated systems that really should've been revamped during the development of ARR, so please work with me.
That said, if gear were automatically added to the closet at pickup, that's another reason that they'd have to rely on having a constant lookup for. We're trying to avoid that, so I propose glamour prisms now be used to create an item that copies the basic gear (don't retain the dye on the copy, else that's even more to track, we'll deal with dye later.). This item can then be added to the glamour dresser when you visit to add the look.
I know a lot of people here have said "Make one dye item" or "Make one dye for each color set." I'm kindly going to disagree as, despite how cheap the dye actually is from the vendor, it does help take gil out of the economy. But since we're revamping the dresser anyways, why not add a dye bank to it? Store as many dyes as you want in there (or maybe up to a cap?)! When you go to dye a piece of gear, it looks into your dye bank.
Like I said, I'm not versed in the goings-on of how to program or how spaghetti their code is. All I can do is say things that make sense to me and hope it makes sense to others.