I noticed this post on Massively and I just had to comment. I believe sound is extremely important, and Runes of Magic is sorely lacking in that department - the inspiration for the OP's topic.
I'm always surprised to see those people who say that they play with the sound turned down or that play their own music during the game. Look. You've got all day to listen to your own music - you can listen to your own music a n y t i m e. In fact we are innundated by commercial mainstream music practically non-stop. And you mean to tell me that you like it so much that you simply must have it playing while you game too? Instead of the music designed for the game?
Music (and the incidental sounds) are a large part OF the game imo. If you are eliminating a part of the game that can have such an emotional impact as the music, then you are not really playing the game. Just a part of it.
Now I've played WoW for 14 hours straight before and yes I have turned off the game music, and I always do during raids as well. But those who just always play games without the sound are not "true" gamers in my book, and even more importantly are depriving themselves of the full game experience. Computer games are made up of two things: what you see and what you hear. That's it.
What you can see in the game.
What you can hear in the game.
Thats it! There is no tasting there is no smelling there is no touching. Just sight and sound. Eliminate the sound (and replace it with your own sound) and you're only getting half the game.