I would like the ability to say to my ISP "I have a little traffic that I would really like to be delivered on time every time. It's not much, and I'll pay you a little bit extra for the extra effort." (Gaming/skype traffic).
On the other hand, someone downloading large files or streaming netflix (with its deep buffers) would like the ability to say "I'm going to be transferring lots of data, but I really don't need 100ms latency for it; long latency on my netflix stream is fine, so long as the time-averaged bandwidth is enough. Since you can give me what I want with less effort per megabyte than the guy who wants 50ms latency, I'd like to pay less."