Fleet/amenity consistentcy is difficult with a very large fleet (and assets used for 25 years) but it wasn't a priority for AA before the merger, and isn't now.

There's a U.S. carrier with lie-flats & aisle access business seats on all long-haul widebodies. There's a carrier with AVOD at every seat on those aircraft types. There's a carrier with business lie-flats on all TATL 757s. There's a carrier with wifi and Y+ seats on all RJs with more than 50 seats. None of those features is true of today's AA.

AA execs haven't even committed to real Main Cabin Extra across the US-origin fleet apart from the 319s.

That the OP is a long-term FlyerTalker of PHL residence and complains of US-origin A321s is very ironic.