This really needs to be an optional feature. Regardless of what the intention of low level zones has been in the past, they've evolved (and have even been designed quest-wise in most places) as rather solitary singleplayer areas. People expect, and some have even grown to like, that quieter atmosphere. It's useful for farmers, rare mob hunters, roleplayers, and just those that prefer getting away from other players for a while.
It's a great feature, but by making it always-on it's going to alienate a bunch of people.