As someone who likes to play Brutes (and Dominators) more so than other ATs and was in the CoV beta test, the perception of Brutes being the CoV 'Tank' was made by the Community after it's launch, but started it's momentum towards the end of Beta when they started allowing more people in.
The original intended 'Tank' for CoV was the Mastermind with Brutes filling the off-Tank Scrapper-like role, but that never really panned out, on the Servers I played on at least.
Masterminds were few, at least the ones wanting to group, and if you were a Brute and joined a group, they expected you to Tank, no matter your Powersets. I lost count of the times my BA/SR Brute face-planted because of this and before it got fully IO'd out.
I'm not going to argue with anyone about buffing this, nerfing that and so on because I've not played since the shut-down and have only been back for 3 months and there's so much that has changed and or been added that I'm not fully up to speed as of yet. I've remade my BA/SR Brute, but it's only lvl 8 because I've been too preoccupied with leveling my Dominators and SJ/Rad Brute, which has decent survival for only being lvl 40 with SO enhancements.