What's the deal with the damned contracts?

So here I am trying to get a good plan for a cellphone. I have set up a phone line and DSL with Verizon. I originally wanted to go with them for my cell phone service as well, but I would have to get a new phone (ka-ching, ka-ching) so as of yesterday I was thinking of staying with Sprint, so I wouldn't have to change phones. I had my number shut down yesterday, but they will keep the account open until the end of my billing cycle. So I called them today and they won't let me do anything with them unless I set up a two year contract with them. Mind you, I have been a Sprint customer for 2 years now. And this is how they treat customer loyalty?

Like Earthlink. I had infi.net originally which was bought out by Earthlink, so for all intents and purposes I have been an Earthlink customer for 9 years. I get offers in the mail for sweetie deals for NEW SUBSCRIBERS ONLY. Companies today encourage you to jump ship but offer NO REWARDS for loyalty. Since I'll have to get a contract anyway with the new provider anyway, bye bye Sprint.

We don't have to have contracts with Microsoft or Apple or Exxon or Chevron. So what's the thing with cellphones? Who did they sleep with in congress to come up with this idea?