IDK if the "horrible Y experience" is AA specific albeit AA appears far worse than DL, UA and WN. When management decides to squeeze more and more seats in and charge for more and more to a FA mind (particularly a young one) it says we just don't care about Y paxs. They're getting a cheap ticket and are really nothing more than a bother and a drag on the airline. Of course AA's dismal operational performance and decision to rip out/not install AVOD only makes an even greater impression.
In the end Wal Mart prices get you a Wal Mart experience. Unfortunately many of those Y paxs aren't paying Wal Mart prices and some are very profitable to the airline (CKs, EXP, PPs aren't always riding in premium) and that's what AA management seems to miss.