To me it seems this is getting to be pretty much the same argument as "should healers damage or not". And the rule is about the same, for healers it's about downtime, for tanks it's about excess hit points. No healer appreciates the " paper tank", that is those who have less hp than, in some cases, the casters of the group. But when they have well enough hp to do their job properly it's not wrong to add in STR to smooth things out. As much as healer should not be dps'ing when the party needs heals but otherwise is usually welcome to make some boom.