My quick dot point response:

1. The OP post suggests Yoshi's team are changing things in the game to make it different to what the OP has always enjoyed in FF14. That isn't the case. If anything they have been perhaps too true to their formula. Regardless, they never made any promises to change FF14's system to the one the OP wants so its rather unfair to accuse them of alienation. You don't go to a megadeath concert and then complain that they aren't playing One Direction songs.

2. Substantial gameplay and itemisation changes add a lot of addition cost in resources to development and have substantial risks that if fail can alienate everyone. No one likes playing a broken system regardless of its design. That means resources coming out of other things. Since we lack metrics to really fairly make a call on the popularity of such a change we can assume the SE (who does have more acturate metrics) has a much better idea on if such a change would benefit the majority of their playerbase to take the risk and the cost involved.

3. Just because a system isn't how you like it doesn't mean there aren't people who do like it. Likewise the system you like isn't necessarily a system that will be popular over all.

4. The fundamental issue that has lead to WoW's decline has been poorly delivered content, not its itemisation or difficulty. Infact WoW has actually been accused of making grindy 'optional' items like their quest chain legendaries that raid groups treat as mandatory for people to do mythic raiding. This makes it very difficult for newer players to join in in Mythic raids.

5. Horizontal progression systems have a lot of potential drawbacks. I personally am really not a fan of them. I find them frustratingly complex and they tend to be a nightmare to balance to high performance difficulties without forcing people into mandatory build anyway. When I play a game I don't like having to have to go reference a third party website just to know if gear is viable at all every time I receive a piece or if my build is still viable every time new content comes out. That's not even starting on having to have different armour sets for different content and all the space that takes up.

5. FF14 isn't FF11. FF11 is a different game in a lot of ways and was build quite differently. While it might have some ideas that are worth adopting and perhaps FF14 could benefit from more variety, FF14 isn't going to adopt FF11's gameplay. It hasn't been built for it and their development isn't structured for it and it would requires a much bigger overhaul on the back end than I think people realise to adapt 14's systems to be more like 11s. Just look how tricky things like allowing us to stack multiple dragonskin maps is.