"Huge lack of tanks and healers in the game"

[Canadane]

Theres no tank shortage.

There IS a shortage of tanks willing to put up with PuGs in the DF though.

This is pretty much it.
I know way too many people who straight up won't tank in DF because they either can't take the pressure of being in a lead role or can't stand the poorer performance found by randoms in a dungeon.
I personally just love tanking, it's my favourite role and I love to have a great time. I don't get upset at the poor performance of others, I mean this isn't savage stuff we're in. But it seems I'm somehow in a minority.