UO is/was pretty unique. It had poverty. Some players were so poor that they had to beg for food! Funny and depressing at the same time :)

Overpowered players were really rare (in the golden age, at least). And they were usually very famous, like celebrities. It was very very hard to improve your character's skills. The game wasn't tailored to boost your ego with custom looks and mean-looking armors and weapons - it was what it was, and that usually meant frustration.

At least for me, it was fun and unique. I don't see anything like that in the current generation of blockbuster MMO games.