"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." -Manuel II Paleologus
I think the destroy-Bush-at-all-costs crowds is the results of a gimme-NOW generation. They have never learned to have to wait for anything, so they never think past today, the moment, themselves.
They are angry because they see Bush as the hold up to putting someone in power who will give them all that they want for the moment, and they can't see past today to know what the results of taking out Bush will ultimately mean. They don't think of it as destroying America, they proclaim that they love America as much as anyone.
Its the same thing when they go spend their latest paycheck on a new TV or cell phone rather than thinking about where the money will come from to pay the rent next week... or retirement down the road.