We Philadelphians have longed for a consistent lie-flat premium product to the West coast for decades. The numbers must not be there to market a dedicated service, otherwise it would have happened. They're not going to sub a standard 321 for a 321-Transcon on a JFK-LAX/SFO route. But they will sub a 767 or even 321 on a PHL-LAX/SFO route that's got a 332 assigned if needed.
This reasoning is why I adopted VX and hung in there as long as possible. Mu goal is PHL as that's home. I'd much rather trek to the office (Asbury Park, NJ) from there than from JFK or even EWR. Growing up we hated both "New Yorker" airports and loved our Philly airport services even if deficient. We accepted it or didn't know any better once USAirways moved the hub from Pittsburgh to Philadelphia.
AA must know the need is there if they're tracking and trending F/J purchases vs. upgrades when the A332 and 767 is in the rotation as well as the routing of passengers that are no EU to/from bound. (like me).