Actually, revenant's toll is emptier for 2 reasons (both due to 2.1 patch):
1. Cities and housing give rest bonus, so there is no need to stay at a sanctuary like revenant's toll for a long duration
2. There is no need to shout anymore due to party finder, so people don't have to be in the same zone (such as revenant's toll) to find party.

But yes, instances give more exp so more people are in instances rather than not.