There's a lot of fun stuff from FFXI that I would love to see translate over, but exp parties isn't on the list. Limbus/Dynamis, open world enemies that you run around because they can do worse than hit you with heavy, gear that remains relevant for years, convoluted maze zones where noobs get lost on the way to fighting big monsters, people committing suicide to get a tractor/raise rather than navigate through those maze zones...