Voting for who you wanted gone might be more problematic. I have no doubt that the cell phone (text messaging) teenie booper crowd is by far the largest voting block. Look at who doesn't get kicked off...people who would appeal to teenie boopers.
Its a lot more honest than voting for retention. No singer can be retained because of a cult following. Only at the last, when it is down to the last two, should the vote be for the one you want to be the idol. The rest should be negative votes. Weakest link type.