Why Is There Still No Volume Slider?

It takes about 5 minutes for most flash game dev's to create a volume slider for their games. Why do we still not have one?

I know most people are ok with "on" and "off" being the only options, but some of us listen to music / watch television / or produce other work while playing Settlers, and it simply isn't good enough that there isn't a way to turn out volume down. I can't count the number of times I've wanted to hear the game 'a little bit', rather than hearing WALLA-JA-BEE-WA on full blast when I start searching for a new mine. And i'd rather not mute it due to running adventures and needing to hear interceptions and attacks going on.

Is there any way we could get this option implemented in the future? I'm just curious on why it would have any sort of downside.