I think what is personally frustrating for many of us is that (right or wrong) the market performance of a game released 15 years ago where numerous poor business decisions were made is used as a referendum on design concepts that matter to us without regard to execution and presentation. It's a call to suck it up because we are not worthy of having a game that suits our preferences. Sit down. Shut up. Be happy with what you are given. There is no room in this big tent for you unless you give up on the things you want.
I know there is little sympathy for 3E/OSR fans because they had Pathfinder etc.., but at the time of 4E launch "
suck it up because we are not worthy of having a game that suits our preferences. Sit down. Shut up. Be happy with what you are given" was used against them. I fully understand that 4E was on its back foot from the moment it launched, so folks had to fight hard to defend it. Though, a lot of those defenders were very arrogant and elitist about it. Many still are to this day.
Things like tight system math with robust encounter and monster/NPC building, mechanically compelling martial classes, meaningful and binding non-combat features and rules for stuff that is not magic, high level martial classes that feel suitably high level, class design built with synergy and coordination in mind, setting design built with conflict in mind and other features we consider important are treated as if they are already settled matters that are not dependent on execution, presentation and a fluid market that is fundamentally not the market of 2008.
Devil is in the details on these general ideals. How it is accomplished is much more difficult. There can always be too much 4E in D&D and never enough at the same time for the fan base. Designers have to grapple with that chestnut a newly forged sacred cow thanks to the E wars.
It’s not that people are saying, “4th edition rules were not to my taste, for these reasons, and so I avoid that edition.” It’s not that people are saying, “4th edition was unsuccessful for these reasons.”
Funny thing is now, folks are saying 5E sucks, but just got "real lucky with its success for these reasons." This is the edition war now where validity and worth are measured only in success. Another new sacred cow?
In my opinion whatever people think of 4E isn't interesting. Feel free to hate it or love it as much as you like. My chief concern is how 4E is always used as an argument in certain discussions as a reason for why we cannot use method X or Y to solve a particular problem, because X or Y is vaguely similar to something in 4E and since 4E is bad (apparently) doing X or Y is also bad.
Some of that is covered above. If you let up on 4E for a second, you invite it back into the tent. I'm not saying that, I'm just saying.
Though, I want to take a moment and discuss e war terminology trap that folks fall into. The words "problem" and "solution" are very loaded. In this thread or one adjacent we had some one post, "you people wanted this problem solved, but then had the audacity to reject the solution". 4E fans and non-fans alike are not a monolith. Problems in D&D are often one of perspective. Not every problem is universal, and not every solution is the best/only answer. If you "fix" something you could be breaking something else. Folks often want their pet peeves addressed and don't care about the results for anyone else. Which is why I try to understand others perspectives and only speak for myself on these edition topics.
I dont envy the designers at all. You have to gauge the desire for things to be changed and the impact on all of those decisions. You also have to present in a way that is not 4E at all, but also totally 4E. Dammed if you do dammed if you dont.