There was a lot of talk that the LAX-MIA route justified something special due to the entertainment industry premium demand and AA ran a decent mix of widebodies for quite a while. Now however they decided to just send nearly hourly 737s due to the total lack of competition. At least LAX-JFK has UA and DL offering a decent product to compete but to Miami the only true competition with a superior premium product is B6 and VX out of Fort Lauderdale. The only thing that will force any airline to upgrade its offering is competition and none of the routes you cite provide any true competition for AA premium customers, thus we can expect to see plenty more brand-new planes with no amenities and tighter pitch. Just look at how they have outfitted the new 737 Max. What an embarrassment for a brand-new plane for the next 25 years!