I guess the reason I don't like the Zips playing against FCS competition is more basic than a strength of schedule argument. I don't like the idea of 85 scholly schools playing 63 scholly schools, or however many FCS has now. While everyone tries to talk about how different P5 and G5 are at least the rules for composing their teams are basically equal. That is not the case when comparing FBS and FCS.
I get that many schools, even P5 schools, schedule FCS teams in part to ensure bowl eligibility. While I wouldn't go as far as saying FBS schools should not be able to play FCS opponents I do wish that FCS wins did not count toward bowl eligibility. Then you would see more P5s knocking on the door to schedule G5s and a good recruiter at a G5 school could use that to his or her advantage.