Sacred Haven of Debauchery

In PvE, there's always a priest and a controller nearby.

I know exactly four decent priests in WoW, three in EQ2, one in RO, and one in DDO. But they aren't always around, and the rest are often incompetent mutants who can't even heal from three or four mobs, let alone a group.

Aggro is maintained with just two or three buttons.

If only it were that simple...

In PvP, there aren't even groups of mobs, just a lot of HP and it's hard to kill.

You must be running into bad killers. Or, you're a bad killer, depending on what you're playing. There's a lot of HP that gets chipped away fairly quickly, but killing someone is very difficult.