In this case, I really don't think there have been better ones. Many have an idea or two that are really good but the game as a whole is bad or a failure. The only other successful ones hit more niche like EVE and really embrace that niche.
Well, that's just it; how do we define "better"? Is it more features? More content? Different systems?
I guess I'd posit that the games that have "failed" have done so because even the tiniest of bugs or balance issues or rough systems are treated by players as insurmountable problems. WoW wasn't looked at with that critical eye when it launched because it was measurably better on every level than the competition. If players try these new games at all, it's under the premise they can just go back to WoW, and most of them are looking for a way to justify doing that, because they really don't want to let go of their equity.
Of course, that's not everyone, but that's been the pattern I'd say generally since about 2007 when the WoW competitors truly started to hit. And each year, it does become less and less of a factor, with WoW having even larger drops in subscribers who return for shorter periods of time.
But even then, are these players going to a new game or doing nothing at all? Seems like the latter, even though there are some great options out there.
WoW is at a point in its product lifecycle where it's definitely dated; mechanically, visually and so on. But because of the nature of the beast, it's hard to leave it behind -- but not for the right reasons. Players will continue to play it in spite of the amount of fun they have because of their equity; progression, habit, and friends.
