In any sort of open-ended game, such as tabletop RPGs or MMORPGs, there are some mechanics governing how you can interact with the setting. There tends to be two ways to go about designing such mechanics: the first is to use a very abstract, general set of mechanics that can model, in some way, any type of situation that might crop up; the other is to build specifically towards the style that you want the game to feel like. The two methods aren't mutually exclusive, though the ideas behind them sometimes diverge.
The most important thing to remember with regards to this is that any game will be played in a way that the mechanics promote. If you build a game with a system that presumably governs everything, but spends most of its time detailing physical combat, one can hardly claim to be surprised when physical combat turns out to be the thing that the players do most of. If one wants a game where physical and social conflicts are equally important, then do not weigh the mechanics one way or another! Make them have equivilantly important consequences, no matter which way the player might decide to go.
This applies to MMORPGs as well. In most of them, combat mechanics dominate the game. Thus, despite the designer's intentions, it is not very reasonable to complain about people not spending enough time participating in RP, or people spending too much time attempting to optimize their combat ability. Similarly, getting shunned by using an unoptimized character setup in a game that promotes certain victory conditions that require is reasonable in sense that there is no mechanical reason to bring somebody that may be a liability to the group's success. Hope you're a persuasive or personable person!