By fold out couch I assume you mean (what they call) the "jack knife couch." We have one in our 2006 Cougar 289EFS in the "bunkhouse." The darned thing is useless as a bed for the reasons you stated. In addition to the higher back (when folded down) there is the gap between the two cushions that make it difficult if not impossible to use as a bed.
I have contemplated removing it and replacing it with a futon or some kind of single bed; as soon as our Son outgrows the bunk, I'll look into doing that.
In answer to your question, it seems that they are all like this. If anyone has had any luck using it as a bed I'd like to hear about it. Perhaps someone has a modification that makes it usable for sleeping?
As it sits right now it's just another seemingly good idea gone bad!