I will personally be switching to the tanking cloak and the tanking metagem. I might even do it for my monk, since it's going to be another cooldown to use every 2 minutes, and the meta is being changed to 20% flat damage reduction instead of just physical.
Fortitude The proc is also "roughly 2.57 ppm" or roughly 38.55 seconds out of 60 or 64.25% uptime (according to the tooltip for the gem)
On a "progression" level, there's no reason to look at it and say "I don't care about surviving, I want to do the most damage possible!" To which I say, re-roll a dps class. Your #1 thing to do as a tank is to survive, if you choose to go the dps route instead, you give up that survivability. Not everyone will go into T16 at a 11/13H or 13/13H level, I'm sure there's a lot of people who are going in at 3/13 or maybe at best 8/13. There will probably even be people going in at 11/12 normal progression level, these are the types of people that will really need the tank cloak/meta, because it will help them survive that much longer and to be able to make up for their mistakes.
We're not perfect, we do make mistakes. If you can tell me you've never made a mistake on a progression boss kill that caused you to die, then perhaps you can continue using the dps cloak/meta. The bosses hit hard, there are lots of abilities that will destroy you, do not under estimate the next tier and gear for damage over survival. ToT was somewhat of a joke for tank damage, don't expect them to make the same mistake again.