I never said MMO players are all content with prefab options. I only said that tabletop players generally are not.Hmm. I wouldn't be so quick to categorise, if I were you! A significant section of the MMO community loves nothing more than to tear apart the math behind a game's systems and eke every advantage out of it that they can. In many ways, they're trying to have the best of both worlds: the closed systems of an MMO, and the pliability of an TRPG.
There are a million reasons you might choose to play MMOs, and only a few to choose tabletop games. It's reasonable to say that anyone who does play tabletop puts a high priority on one of those few things. That doesn't mean MMO players don't put a high priority on those things--it doesn't say anything about MMO players at all.