So, you want to return to 2.0 or 2.1?

It can be done, but you need to be rooted. And you would need to use a computer and SD card to do it. That's the only way I know how to do it anyways.

 

An analogy: you can download all the programs you want, even on a wireless connection, to your windows or mac laptop just fine - but you cannot download a downgrade from windows 7 to xp nor from snow leopard to tiger.

Android is not a program, it's an operating system. As such, it is not relatively east to uninstall the full update, and you will needs a computer to do so.

Furthermore, reverting to a previous stock image will make your phone start to receive messages about upgrade available repeatedly....

So, tell me, what don't you like about 2.2 anyway?