Never underestimate sounds. The most likely reason you don't think that they're important is that in most video games, the sounds are good enough that you don't even think about them sounding wrong or fake... you just enjoy the game. You sure notice when a sound is poorly done or out of place, though. I remember seeing a review of some game that mentioned there were only two footstep sounds in the whole game, so the entire time you hear "pit pat pit pat pit pat pit pat pit pat pit pat..." over and over, driving the player mad. You might not think of the footstep sounds in a game being very important, but if your character is going to be running around all the time, then it suddenly becomes very important!
