Well, obviously the people paying for them want to. I mean, it's possibly the most useless thing ever and there's no utility. It's for idiots.
Strangely, Keith and the Girl were talking about this the other day. They're "full time" now (think Penny-Arcade) and so they scrape together little things to make money. They recently put together a bunch of ringtones for people to buy (mostly, these make fun of people with ringtones). The interesting thing is that Keith was saying they basically get no money for it. His exact words were "what a racket!!". The hosting site takes 50%, which they thought was 100% fair. The racket part comes in with the providers. They take another HUGE chunk for pretty much nothing but allowing access to "their" phones...which were made by a hardware company. Insane.