I doubt they are intentionally doing a bait-and-switch because they're evil, but when they make the same change month after month AND it meets the definition of bait-and-switch, I don't think they can hide behind the contract of carriage. Every contract contains an implied covenant of good faith, i.e. each party genuinely intends to perform. I'll stop there.
I did call ExPlat reservations and the AAgent basically said "Pay the fare difference, there's nothing else I can do."
I'm less irked than I was two hours ago when I posted this. It appears that they are putting a 787 into regular service, at least for several months, flying westbound at 6-7PM and eastbound at 10-11PM. What this means is that I can get my lie-flats in both directions without even having to take a connection. I already changed one trip, having to pay an extra $21 each way. There's another trip where I was on the 4PM nonstop and it seems like they are probably changing that to a later nonstop on the B787. There is a separate post about new widebody schedules, and I'm hoping that they don't post those schedules capriciously.
All things considered, this is kind of nirvana for me. If you asked me what is the one thing I'd like AA to do, it would be to fly widebodies in both directions PHL-LAS. On the two trips I took in 2020 before the lockdown I was able to get that configuration, but I didn't see it as a regular thing. I may just pay the $190 here rather than fight it to the death because considering everything I feel totally ahead of the game.