I see people in lower level zones all the time. The rewards actually scale fairly well now. Unfortunately, I don't have a screenshot for comparison, but I remember the rewards for doing Orr events vs. doing them anywhere else were negligible. I do know that they buffed lower level events to scale better with your level and that they've nerfed the Orrian events apparently several times now, which would probably explain why I usually get 0 drops from any of them. Personally, I have my farming character parked in a level 35-45 zone where there's a semi-reliable event chain. I take a small hit to EXP and karma, but in exchange I get to not have to deal with Orr and actually get drops off of most things I kill, so I feel it balances itself out.
Apparently farming champions in Queensdale in particular has become the 'thing to do'. Not really sure why, but there's a sizable group on my server that just keeps making the rounds between the champion events that spawn there, especially the troll.
I will say a lot of the mid-range zones do feel empty, especially if there's no sort of continuous event chain for people to follow.
As far as community, I can only speak for my server and my personal experiences there, but it's nothing like WoW. Most questions I see asked get answered appropriately, I rarely see any juvenile/troll chat (at least outside of Lion's Arch, which doesn't represent my server anyway since I'm always kicked into Overflow), most people will stop and res you, etc. GW2 easily has the best community I've experienced in an MMO.