UA has always been the leader with their extra legroom seat count, and they seem very happy with what they have. And currently, DL is adding additional extra legroom seats to some aircraft.

Interestingly, UA’s Coastliners are supposed to have a similar seat count to AA’s XLRs, but with a substantially larger extra legroom Y section. So UA is likely sacrificing some legroom from regular Y to fund that (in addition to not having a bulkhead behind premium economy).

I hate to say I agree with UA’s approach here, but if AA is allocating more legroom to regular Y on the XLR, they’re unlikely to get a fare premium for it.