1) The idea is that, as a prot pally, if I'm going to MT I need to put personal survivability and threat gen above group utility. BoSanc is definitely a better tanking blessing now and even giving it to everyone raidwide will lessen the burden of healers.
2) It's located in the first tier of the prot tree so it's attainable by anyone.
There's another thread on this exact topic, I suggest we move this discussion there.