More items to collect, Diablo 2 had runes, superior, socketables, jewels, charms, ethereal, ebugged ethereals that would get a random amount of sockets, etc. Low level sets and uniques should be more common. People like to run through early levels twinked and feel super powerful. More possible mods (Diablo 2 probably had 3x what D3 does, funneh). Also, people like to plan out gear, so if all the uniques and sets are kind of meh, and rares are always better people have no idea what to shoot for. More rares with main stat, vit, res all, not exciting.
Something to grind at end game. A heavy, nearly insurmountable grind from 60-70 would suffice. Give just a small stat bonus per level here. If you can't do that, one of those youtube guys advised warrior levels or something, just give us some sort of progress for playing, I think it is quite a turnoff to most players that someone who has put in 100 hours and a couple hundred $$s can have the exact same level and gear or better than someone who has been grinding mobs for 500 hours. In Diablo 2, players who didn't mf at least had to leach in Baal runs or buy a naked character from a website. Heck you could have the RMAH include the sale of leveld characters. Characters must be naked to sell and transfer a character over, sold characters include one name change. Boom, you did it.
I have been spewing this rant across the forums off and on for the last week or so as I loved D2 and would love to love D3 :P. If you guys could just recognize that there is an issue with the end game and announce you are looking into the problem that would be great!
The skill tree is ok. Heck Diablo 2 has respecs and the stats in Diablo 2 were "try not to use any stat points except in vit unless you are max block, then enough dex for max block and everything else into vit". So they are essentially the same, although I did enjoy the skill tree and stat points.