For me, this is another way that 4e achieved what it set out to do, which was to create a TTRPG experience somewhat similar to an MMORPG experience. In an MMORPG the monster encounters are the whole point of the game. Everything that you do is about improving your character's ability to succeed in the big boss fight. More specifically, the raid encounter. And those fights have various stages, so you have to plan your cooldowns (on use powers, in 4e terms) accordingly, and so on.
I think that 4e was broadly successful in creating a game that captured some of that feeling. But that's not D&D is, for me. For me, D&D is a much more story-driven game. In our last three sessions at school, there has been exactly ONE combat encounter - there was potential for others, but the players found interesting solutions. And they have been having a great time.
You could do that in 4e, but it felt like the point of the game was to prepare for set piece battles. Very much like an MMORPG. But I was already playing World of Warcraft. I wasn't looking for experience at my TTRPG.
I'm sure the setting changes were a big problem for some folks. They were not even a consideration for me.
One of the reasons I burned out on 4E was because it felt like the structure of the game and combat just kind of sucked all the oxygen out of the room for anything non-combat or for creative off-label solutions. I'm honestly not 100% sure why it felt that way for me. There were a few factors, of course. One was the skill challenge structure being presented, or at least interpreted by many DMs, as something that should pretty much always be used to resolve stuff outside of combat.
But a big part of it was the narrow focus but ever-increasing multitude of powers. You couldn't swing from a chandelier (unless it was part of a skill challenge of course) because someone out there might have a chandelier swinging power*. In addition the powers were so detailed in what they could do that there wasn't much wiggle room for creativity or using it for something different than exactly what the text said.
That, and at higher levels combat took hours. Heck, we timed it once and in an epic level game a single round took a little over an hour.
*Obviously silly example is obviously silly. But I was told more than once that I couldn't do X because it was something that others could do because of a power. After I was told that a couple of times, I stopped asking.