Amoenotep wrote:everyone of those places you listed that you lvl regularly...is also on a someons pk route because its the easiest place to go
That's so true. I never solo the mountain because I remember all too well how pkers liked to prowl there.
Hell even I've prowled there recently because I was bored, but all I found was Twig.
Keep in mind that people party at the mountain and FD because they're easy to get to, and there's a bind point nearby if you die. It's convenient because you can round up a party in 5-10 minutes instead of getting a party together, then spending the time to travel across the map to get to a more remote leveling spot. It's a bit quicker these days with the ferries and dragons, but the mountain and FD is still easier to get to. That's probably one of the reason people go to Dwarf Home too...hop on a dragon to Angmar Wastes, bind if you want, then walk 3 zones to the rift. Or in my case, I usually log my toons in my guild hall, so I just have to saunter across the lower stronghold and take the fast way up. The RK rift isn't deep in a dungeon somewhere like most of the others, and getting to it is fast.
Even if you tweak the XP formula, I think people will still go for the convenient spots.
Also, I think it's not so much the XP you get per mob that matters, it's how much XP you get over time. If you can kill lower levels mobs faster and get more XP for the time spent than stronger mobs, than it's more worth it, and less risk too. Also keep in mind the type of fights involved. Giants/Efreets/Dwarfs are mostly melee mobs with few special tricks, that makes them easy to kill unless they have a lot of DR and/or hp. Compare that to mobs that have a lot of strong ranged attacks or magic and those tend to be more of a pain to kill.
As for 35-40 being a character graveyard, it might not be a simple matter of grind. People possibly abandon toons at that point not because it takes forever to level, but because there are flaws in the build that become more and more noticable. Maybe the toon looked good on paper or a spreadsheet when you put it together, but in practice it sucks. The AB is crap and you can't hit anything, or your AC is rubbish and you're constantly taking hits. Maybe your selection of skills and feats aren't panning out as planned. So tweaking XP won't help here, even if you get to 40 faster the toon will still suck.