Well, there's already 3 volume settings, 2 of which the player can control at runtime.
i forgot to mention that i speak of fullscreen games. when the game is running in a window, of course one can adjust the systems volume simply by two clicks.
with a fullscreen game, one cannot. (also not everybody has sound boxes with buttons on them to turn the sound lower by hand)
Usually, if a person sets their speakers very loud, they will turn the WAV audio volume on the volume control down on their system so those sounds aren't so loud.
of what geek/nerd type of user do you speak? 98% of normal windows users can hardly be presumed to even
know they can right-click and open this special window. to say nothing of they would know what the wave slider does.
And even if the game has a volume control, you're just as likely to hear a really loud sound before you realize that the settings are too loud. Then you're likely to have to quit the game to fix it (so the volume control in the game would be useless). It's more likely that a player will want to fix it without the game running than to leave it running with the loud sound and fix it.
well, different people, different behaviours. if a fullscreen app suddendly comes with a loud music (of course, not so loud it would harm my ears), i take a few seconds time to search for an options menu to turn the sound lower. i don't like it to quit the game, turn sound lower, start the game again, find the sound too loud still, quit it, turn the sound lower, start the game again....
this is my position. i don't think i'm able to explain it better.
your tip (showing volume level to the user) i will take with thanks

edit: yeah you may be right. game makers who care how sound behaves, build it the way you suggested. the others not. maybe this is a point to be discussed further. don't know.
But I don't want to force all games with sounds to implement this the same way, so I don't think it would make sense to hard code it into the options dialog
so what alternative can you imagine?