We should do away with diplomat immunity IMHO.
If we do away with diplomatic immunity would we have to send our Kenyan President back to his home country?
How would that look?
The problem with that is that less scrupulous governments (though, given the current occupation, I'm hard pressed to come up with a long list of those) would then do away with the custom themselves, and trump up all sort of charges against U.S. diplomats so that they can be intimidated and/or interrogated.
The wheels of diplomacy require proper greasing, and it doesn't always smell pretty. Diplomatic immunity works under the tacit assumption that the home country will deal with individuals who abuse it and host countries will sever (or downgrade) ties with countries who abuse it.