He doesn't mean resetting the server or anything, simply that mobs would start spawning in the wilderness again and that weather would happen more frequently.
I actually hadn't noticed a decrease in wilderness mobs, but if anyone would you certainly would Mishai. I don't go out hunting them much, but I do see a few every now and then during my grief reports. Probably not as many as should spawn in the wilderness at night in a dark area, though.