I have to kind of lol at you thinking ORD-MIA would be an unpopular route!
Fwiw I think $140-170 is very fair for that length of flight - I do get where you're coming from though, that which was previously free is now attracting a charge. I think even at EXP level upgrades are now more of a bonus than a given (certainly as a PLT that's my perspective), which from a business perspective makes sense to me because I don't think business travel will come back to pre-pandemic levels which means the US3 are less inclined to pander to that demo and are pushing for status to reflect engagement in the wider AA ecosystem, which again makes total sense to me as a member of a younger generation. I actually kind of applaud AA for a somewhat innovative approach to rebooting their loyalty program.