Yes, if you face inoperative seat or IFE, you should not expect any compensation from UA. The integrated UA customer service team has taken the CO attitude that it is more important to fix the underlying problem, and prove that you fixed it, than to try to offer expensive band-aids by giving passengers discounts on future travel.

(It's not 100% clear that they always do a great job of proving to passengers that they honestly intend to fix the underlying problem -- but this is, I think, their goal.)

Are you sure the "empty J seat" that a flight attendant ended up taking wasn't the contractually mandated "crew rest seat" being taken by a crew member?