In my opinion there are two reasons, why it is very important to teach evolution.

1. It is extremely important for medicine/drug developement.
For example, if giving anti-biotica to a patient, it is very important to understand how bacteria will build up resistance to that, in order to avoid that. And that simply is evolution/selection.
Another obvious thing to me is, the necessity to understand the spread of certain pathogens from one species to another. Just think of bird flu, which spread from birds to humans. Or HIV, which many people claim to originally have been an ape disease. That is also evolution and can be vital to understand.
A third thing is cancer. Cancer is caused by your on mutated (evolution) somatic cells. So, to early recognize (and in the future hopefully to prevent) cancer, it is crucial to know what exactly happens and why...

2. I think it is generally a poor thing to forbid teaching of an accredited thesis. Even of a more controversial thing. Of course it is necessary to also mention and discuss doubts concerning evolution. But I think it is wrong and even dangerous if one group in society tries to totally deny you access to knowledge, dissagreeing with their believes.