After leveling everything to 80:

When I tank, I wish I had healed because other healers generally aren't that great.
When I heal, I wish I had tanked because other tanks aren't that great.

Basically there are a LOT of sub-par players in this game. I don't mean at the EX / Savage level. I'm talking basic Dungeon Finder players who don't know how to play their job effectively or are just lazy.