For connecting passengers there may be a separate calculus. Connections at MIA between AA and LA were not easy for us last year --- we recall it being a long hike between concourses, and our connecting baggage was mishandled/delayed (despite a >2 hour connection at MIA). Also the computer hand-offs between LA and AA were poor from a passenger's perspective. I agree totally re the superior LAN inflight experience in J, but for some connecting passengers it just might not be worth the hassles.