To give a monopoly over the truth to Evolutionism would be as destructive as giving a monopoly over the truth to ID. Who is to say what the truth is? Rather, when students are exposed to theories, no matter how well-supported said theory is, they should be given a taste of opposing theories as well, and encouraged to think for themselves and draw their own conclusions. No one theory should be taught as unopposed fact.
I mean, who knows? Darwinism could turn out to be wrong, we might just not have all the knowledge yet. If you lived back when all the scientific facts seemed to point to Geocentricism, would you have insisted that heliocentric theories be banned from presentation in schools?