I find it interesting that, when speaking of MMOs, one thing I consistently seen in multiple games for years on end is this insistence upon "Endgame is the only game." Where D&D-style games exist (Classes, Levels, Gear Progression), players consistently hate the level part of it. "Leveling sucks." is a decades-long consistency in revealed preference, yet they're still in the game.
You see this in online action RPGs such as Diablo 3, where the endgame is nothing more than competitive dungeon crashing for loot drops on ever-increasing levels of difficulty. Even the preferred mode of playing new characters (roll a new one, get in a boost group, be power-leveled via free-form world/dungeon crashing) reveals this as what players (in aggregate) want. Hell, it's gotten around to the tabletop side of things to varying degrees.
And yet the games themselves refuse to adapt to the clearly-defined revealed preference of their users. This too is consistent. It's a stubborn refuse to admit that the product produced doesn't properly satisfy the audience, so they double-down time and again; they refine, but they don't actually adapt.
I figured out what the problem is: you can have leveling grant power progression, or gear, but not both. That's the problem; when combined, as usually done (that caveat is there for a reason; see below), power scales upward out of control and trivializes gameplay. Players, by eschewing leveling in favor of endgame, reveal that they want a static baseline; by focusing on gear over levels, they show that they want to earn their rewards- and that the rewards need to be concrete on multiple levels to be satisfactory. (They need to be (virtually) held-in-hand, and they need to offer significant and easily-perceivable power boosts.)
In short, the frequency of the reward interval needs to be infrequent enough for the reward to deliver proper satisfaction for its acquisition and it has to both be externally perceptible as a reward as well as internally in terms of upgraded performance. Guess what the older D&D editions got right?
Done properly, you spent plenty of time--real and game--at a given level before advancing to the next. As you leveled up, time-in-level increased significantly. The only way to cut this time down was to take the risk of facing greater challenges, and in that same properly-run game that became a challenge to itself; you had to actually find them first, and then you had go to them in the hopes that another party didn't beat you to the punch, during which time you had better have done your homework and prepared accordingly to beat the thing. In Original and Basic D&D, this was more implicit than explicit; AD&D laid this out better, but still unclear to anyone not already immersed in wargaming campaigning and the mindset required to succeed therein.
The problem today is that leveling is too fast, in both tabletop and videogame media. The knock-on effects of using levels as a lazy marker for content gating are a consequence of this error, but I think there is room to argue that eliminating levels entirely is now a viable option (especially in videogames) in favor of what "gear progression" represents (for power increases) and mere proper tracking of time and deeds done for content access. (Can't explore the Tomb of Bob the Pozzed if Bob is still alive, or not pozzed, or even in the area.)
I've said this before, but it bears repeating: Do You Know What Your Mechanics Actually Do? Too many of you don't, and you wonder why your users don't play your games the way you think that they ought to; revealed preferences show what your design actually does, and why the users like (or don't) what your game actually does. If what they want isn't what you intended, then you have a choice- make your next edition into the game they want, or make your audience into what you intend for your game to satisfy. Merely having ego-fits and just doubling-down won't solve the problem--and it is a problem--because a competitor will use the opening you leave to eat your lunch and steal your audience.
Even if it takes years, or decades, this will happen if you don't kill your ego and properly adapt to what the data reveals. Get humble, and get on with it.