The real fallacy is ignoring that this game can't increase it's level cap indefinitely and alternate forms of advancement will be needed. Character progression is just as important of an aspect in MMO design as content progression 'can be'. Perhaps more so.
Then there's the sentiment that ALL skill/talent/AA systems have to be exactly like they are in WoW because most people have only played WoW or played FFXI. Systems can be developed that promote optimization while still giving players choices. It doesn't need to be all or nothing like so many perceive it to be. Things can be done differently, I assure you. Their ways are NOT the only ways. For instance WoW's underlying issues with their skill trees was an over-reliance on stat adjustments. Where in an MMO stats are basically everything in terms of performance, so of course there's only going to be one 'optimized' path to take.
The problem is most people don't see the forest for the trees. They see one or two systems and say, "Well that doesn't ever work." The believe they already know but fail to recognize their own short-sightedness in the matter. But they're right so nothing anyone tells them is going to change their mind because they're most definitely wrong. It's the ultimate form of ignorance and it's rampant like a raped ape with a fungal infection on these forums.
And no MMOs have become bland because no developer wants to try to innovate. They want to 'play it safe' and use the same design concepts that have been employed for the last two decades. Meanwhile the audience really hasn't changed much. Except for the fact that most of us have gotten older. Got jobs, had kids, got married and no longer have the time to sit in front of a screen for hours on end to grind away at overly complicated content mechanics which are made so simply for the sake of over-complication and not in the interest of making content challenging. Complexity and challenge are not synonymous, although SE and Yoshida seem to be under the impression that they are.