there is sort of a side thing in .hack where the focus is on out of game investigation, alot of real life drama with some of the character, etc. Some of the characters RP in certain ways because it is sort of escapism from their real issues, etc etc.
Yet in SAO the game becomes their real life because they stuck in the game and dying in game mean dying in real life. They are really worried at first (obviously) but after being stuck in the game for months they realize the game is it until it is beaten. People stop RP'ing and everyone is really just being themselves. People get married and such, there is a "real" player police, and while it is only "in game" everyone has to look like themselves. You could see some people choosing the game over the real world.
It is just a different sort of dynamic going on.