I like how league of legends did Olaf one of the tank champion health regen.
He does more damage when he is low on health and regen health much faster .
If we would have tanks like Olaf we could have more agro when tanks are low oh health .
Healers would have to use HoT spells much more . It would favor tanks like paladin and shadow knight
since they can heal .
I think high regen should be one ability sets tanks apart from other classes.