I agree plastic pedals suck. It could be a Trek thing since my Trek 7.2fx also came with rubbish pedals (and rubbish spokes but that doesn't concern this thread).
Problem is, the metal ones they stick on new bikes aren't any better. I've had both on new bikes, and they were always very thin and creaky. Both of them ended up with some play after a few hundred kilometres. Maybe pedals are a hard thing to make reliable? In essence you are putting all your weight on the pedals very small ball bearings.