Tanks in STR gear and Healers being able to DPS are not mutually exclusive. A bad tank or a bad healer or, twelve forbid, both combined create these scenarios.

In full 270 STR and without tank stance on I can self mitigate the castless cleavebusters to not drop below 50% for any of them. If I get an aspected bene shield or an adlo beforehand, it barely moves my hp bar. How many VIT tanks have you seen drop to 15% after a cleavebuster in phase one? Let alone stormsplitters not dropping me below 30%. I can easily survive 5+ seconds after a stormsplitter with only my own mitigation. Yes it's a problem if you're trying to do this without the requisite skill level, but just like you'd yell at a bad healer or a bad DPS you've got every right to be pissed at a bad tank too.

I mean seriously tanks are in such a sorry affair right now that they have to continually incentivise us to get into roulettes. I have 1000x more fun on my bard than I do on my DRK, but I can promise you that I am easier to heal than 99% of the VIT tanks you've run across, and I increase the speed at which the content is completed. It's not just a minor gain. It's the difference between 1600 dps and 2600 dps on a single target boss in 4 man dungeons, and I'm not sacrificing my healer's DPS to do it. I'm even throwing out shields on mechanics to give them more DPS GCDs.

They need to fix the stats on tanks, but in the mean time don't go punishing the good tanks for the crap the bad ones pull.