Well here's a reason other theories that have been trying to get into curriculum should get first dibs on charity spots... (Hi I'm Aaron I'm new!)
ID is USELESS. It doesn't lead to any predictions, it's a system that explains everything with one answer, it has never been shown to be able to accurately predict natural behavior of an unknown.
It's a useless useless theorey, only someone who thought all biology was equally useless would consider it an important subject to cover.
Give the students something they can use... something that will help them in a scientific career, all ID is going to do is confuse them and lead to hypothesis that can't be tested. That's handicapping the next generation of scientists.