I used OrPo (about a Coy) worth in scenario 312 (some were trapped in the Cholm pocket). I think they ahve a place in the OOB but I can't say I use them much...
Can't say I have ever used them, or the Luftwaffe troops, but it's fun that they are included. That being said, maybe reducing troops like this down to a few units instead of 35 slots? That way there is still something in the OOB for a scenario designer, but you also free up some space.