Q:
Did ArenaNet make the lower levels "slower"?
You kind of answered this yourself but events scale in a really weird way, in a full zone they re-trigger really frequently, partly due to they way they are basically offered to someone else in the zone in a place they can’t do them themselves. If you’re the only person in a zone they pretty much never happen.
Anyway since people are moving up the levels these aren’t triggering so often. Fewer events means less xp and slower xp gain. I think Anet in their infinite wisdom also decided to add an xp penalty to alts by making achievements give xp and that xp be account bound.
Oh and the Charr zone is easily the worse for xp gain, though I found the Norn zone pretty densely packed.
You can zone hop to make up the shortfall, or only play when you’re getting daily xp bonuses.
I think its a “your mileage my vary” situation. I’ve done two humans. The first one took a rather leasurely and quiet stroll around the Shaemoor Fields, finishing all hearts in Shaemoor a hair below level 5 and only getting a couple events along the way. On my second human, all the stars seemed to come into alignment and I was getting one event after another the entire way (and sometimes even had multiple events going on either side of me) — and I left Shaemoor Fields at level 7, even though I went through the area faster than the first time.
Grinding mobs is a horribly slow and boring way to level. You’ve got to catch the dynamic events, and if you manage to time it just right that you can catch a wave of events and ride them through a zone you can level up outrageously fast. Unfortunately, sometimes the opposite seems to happen and you seem to hit this dry spell when all the events are still on cooldown.