someone said it best when they said the run between each area (i.e., central to eastern Thanalan) takes longer than a loading screen.
I would trade completely unique zones, full of vibrancy and life WITH a 10 second loading screen, over a "seamless" copypasta world any day of the week and having to travel even longer than 10 seconds between them. As long as SE knows the rest of the community feels the same way and strongly about it, maybe they will put more action into doing it.