When I first played UO back in ~1998 on a shard. I remember the first day, logging in, landing in Britian, there was a 'Newbie Dungeon' and I went in, and died...
I thought holy shit this game blows.
A week later, the zone.com servers were down so I couldn't play AoE. So I logged into UO, and I just don't remember logging out again, I played for hours and hours. The sense of discovery, gaining items, skills, worrying about losing them and trying to be careful, but also trying to steal other peoples. It was a real fantasy.
I remember when the 'blues' had a war with the 'reds' because they were sick of PKing, so they opened portals to the red towns with ~100 people flowing in, lag following closely behind, and reds getting murdered everywhere. For a couple of hours they were just going everywhere in a giant group murdering all the red players as payback.
I've never found a game since that draws me in like UO did. Ever since WoW, everyone has been following more or less the same cookie cutter template for MMORPGS.
There's so much 'content' but the games are a grind to the end to get to end game content, that's it...
The lack of end-game content in UO made it good, PVP was more difficult, and there was risk/reward.
The best thing about UO was that if you didn't play for 3 weeks, you didn't fall behind your friends.
In WoW if you didn't play for 3 weeks you come back and its hard to play with friends, you end up being carried or neglected. Ashes of Creation is trying to solve alot of these problems tho. Fingers crossed that game turns out good.