Great summary of the monster roles and types. It was a really great innovation.

I have a slightly different take on brutes. As you observed, they’ve got a lot of HP and they hit hard (though not well). They’re good for going toe-to-toe with a defender, but I see their HP (and soldiers, elites and solos are good for this too) as a stack of tickets for them to go wherever they want on the battlefield to threaten with their big stick. The defender can try to hit them, but the brute doesn’t really care as he charges toward the wizard. He’ll very likely miss with his attack (especially if marked), but he also might crit, which is going to be bad for that soft target.