You mention core of XIV but you do realize that a majority of XIV's concepts are from other games, right? We can change jobs like XI, gear treadmill like wow with similar lackluster raid progression, and openworld activities known as FATEs taken from rift, just to list a few integrated concepts. Majority of the dev teams original ideas fell flat for various reason but honestly, as I have mentioned before, nothing is properly tested by the public, which wastes a lot of time, but then we have 'white knights' applauding the team for trying. When you're a business, you shouldn't get a cookie for trying but properly testing your products before releasing them to the public. SE in general finds this as a waste of time/money because the feedback wont change them reworking it before its officially released. LoV would've never saw the light of day it was properly tested by the public.
As far as people wanting SOME concepts from XI being integrated into the game that's not horrible. I personally liked Voidwatch since all classes had a role and loot was individualized, plus you got exp/other currencies for doing it. Job point system is great too since it further progresses the class you like and forces you to play that class if you want to advance it further on a skill based level. I believe many people just want to feel different and continue to feel so when they hit cap, not just grind gear and only be defined by an item level that honestly may or may not actually make your class objectively better by raising it. Getting options to lower cooldowns, increase skill duration, lower resource cost, so on and so on.
To continue, Heavensward honestly felt like a let down and rushed at its core. Every class got 5 abilities which either made the class better, worse, or same. I wish it was more subjective than objective but honestly its the latter. We didn't get passives what so ever, nor did I hear the explaination as to why we didn't. Some 50 abilities could've benefited greatly from a passive and some abilities added for classes in Heavenwards are objectively useless in many situations. It just didn't take it self seriously nor follow its own 'core' concepts when you look at how you learn abilities and skills from 1-50. Some core concepts they are trying to do away with such as jobs not having classes anymore. So when you question how silly it is for people to want things that alter the core of the game, maybe you should question first if the core is even stable or continuously changing already.