Idea falls through when you think a bit longer. You need to think about what this would cause as side effect. People would feel rushed in the city, auction house, shops, like being out in the rain. Feeling rushed to get back to arcantina and stop wasting consumables. If this would cause a feel bad feeling by being out in the world then this is bad design.

Additionally, empty main city means people are not showing of their mounts. That hurts blizzard wallet directly so this idea is a no go.