I'd rather spend time in the world running from point to point, instead of just waypointing. But I was the type who'd jump on my mechano-hog or hawkstrider and run from one end of a continent to the other just for fun, sometimes mining and gathering as I went.
I don't need extra speed (though a small base % would be nice, but not more than what any class can regularly achieve), or flight. It's just restful cruising through the world without looking at my poor character running.
It also gives me more stuff to collect. I would rather spend gold on a mount I can keep (even if the price is high) than a waypoint.
If the game isn't meant to be played for an eternity, why make it an MMO then? ^
Expansions.
If folks are burning through the content before new stuff is released (especially from a vanilla release), then take a break until new content is released.