As someone who found 4e "off" somehow, I'd like to add that its outside critique reminded me a lot of the--extremely vigorous--reaction 3e had when it first came out by some elements of the community, without having the advantage of a lot of returnees from outside to to dilute the hostility. I.e. it seemed ridiculously over the top and reductionist in many cases.
The hatred 4e garnered wasn't entirely fair, and some of the more bizarre talking points get repeated to this very day. I mean, I didn't like it when it first came out- I was still firmly ensconced in my fortress of 3.5 books, and it felt somewhat soulless initially.
When I was finally dragged into it a few years later, on the other hand, it felt like such a breath of fresh air! Reasons for monsters to not ignore Fighters beyond "gentleman's agreement" or wacky, specialized builds. Caster/Martial disparity being brought to more sane (if not strictly equal- the Martial power source still had limitations no other source had) footing.
And my goodness, encounter design was so easy, I could focus more on the adventure with my setup- I haven't had such an easy time since 2e, and even back then, I had to strictly "eyeball" critters to make sure my players weren't going to TPK every fight.
It wasn't without it's flaws, of course. They were constantly adding more content to the game to correct imbalances, some classes were much more flush than others with options, ditto for the PHB races versus ones made later. They fixed math late in the edition (which wasn't a big deal for me, but it's kind of weird that they took so long go "oh, yeah, I guess that doesn't work, lol!". And of course, far too many Feats were printed, and a lot of noncombat options fell by the wayside- you didn't know if you were going to need more languages, but by Arneson and Gygax, you were going to need more combat ability!
Social mechanics were weak, but that's nothing new for D&D. What I really found unnerving was how the game mostly ignored non-adventuring things. No real rules for strongholds (you could buy them, but there wasn't a reason to) or investing in the world (you can't break wealth, players can
use that to gain power!). Skill challenges were rarely exciting, and players quickly realized what skills were worth investing in, and how to get strong numbers. A lot of the later options, like Themes, were strictly power upgrades, and some of the later classes were screwy (I'm looking at you, Mr. Vampire!).
I think it was when I tried to run White Plume Mountain in 4e that I realized, this game just couldn't do exploration challenges well, and encounter design, while easy, had a certain paradigm that needed to be followed: an encounter with a werewolf sorceress and her fighter boyfriend, you say? Better make them both solos or find minions for them, or they're toast!
But 4e could have been improved. Instead, they tried to completely transform it into a kinder, gentler game with Essentials, while still claiming it was the same game. And when that didn't work, it wasn't even allowed to retire- WotC did their level best to cremate it and scatter the ashes!
And ever since, the haters run around acting like they were somehow justified in their vitriol, when the real reason 4e bit the dust wasn't that it was the worst thing ever, or that no one played it, or that it wasn't making money. It was because It wasn't making
all the money for Hasbro.