If you're timing's good, it can be faster to take a boat from one continent to the other and back, sailing around the far end, than to take the flightpath from Auberdine to Theramore.
Only humans age/reproduce? There's all kinds of little kids and teenagers running around the human cities, even a few oldsters (no models for these, but they're called "gramps" and such). Every other race seems locked in their prime. I understand some of the races have a backstory where they're long-lived or sterile or whatever, but surely they missed a trick here. Hell, even most of the mobs have different "ages" where the models are scaled differently; Ancient Harpitaur, Snotmantle Runt, etc.