No way will an A321 make it off the ground on some of those short runways in the islands. In my experience, a B757 seems to use every INCH of runway getting out of STT. A321 uses almost the whole runway in CLT (much longer) to get to PHX. I'm not a pilot, but looking out the window and saying "ok, now, rotate" on A321 flights to PHX from CLT's nice long runway, I don't see how an A321 could do the same in STT.
I am certain your comments are heartfelt and therefore I can respect your comments, as wrong as they are.
The four hour flight STT to PHL is fine on a fully loaded 321, the runway length is great. A four hour flight is pretty optimal for a 321.
CLT-PHX is close to five hours and taxes the 321 as CLT is not an optimal airport, too high and generally too hot. It is not that much further south than PHL and is somewhat further west than PHL, we gain little by flying south out of CLT than PHL. Frankly, CLT is a thorn in DAL side and little else other than a fuel stop.
If a B757 uses "all" the runway, it is because, to reduce stress on the engines, reduced thrust is the norm, reduced enough to still stay legal for a given runway length. I have taken off STT in a 757 and both pilots are arseholes and elbows trying to keep from busting the 3000 ft level-off, max gross weight.
The main reason the 321 is not used is because it has no hf radios and no life rafts, which would require a meandering path down to FLA, then, heading off for STT, adding some 20 to 30 minutes each way, not that our pilot group has not tried, six times, idiots, one of which was a union F/O rep highly "decorated" by our company. Jerry Glass gave the dude, on retirement, a job with the Mediation Board. Always looking to violate FARs. Miserable union rep., also. Piece of doo-doo. Got his address if you want to express your feelings.