Okay, I ll make this straight to the point and spare you the whining as I totally understand SD’s approach: Consolegaming is where the moneys is at. The guys in the biz usually let the numbers do the talking. Designers just obey 
You need to adapt.
However, the approach apparently seemed to be to take the ETQW core mechanics and only really change the pacing to make Brink a console-controller friendly game. Yet, even on console, the gameplay is rather dull and very repetative. There are not many different approaches. I believe 4 little changes with a very good cost/benefit ratio could already improve alot:
-To much reload. You re constantly reloading, and it impacts the flow too much. Suggestion:
Slower ROF, more DMG. Or: Bigger clips, less dmg.
-Secondary objective take too long. Long approach, easy to fail. Suggestion:
Decrease time it takes to complete secondaries a little bit.
-Getting around feels to slow, even for console gameplay. Suggestion:
Increase sprinting speed slightly.
-Tertiary objectives are a waste of time. Using MGs vs players who know what they are doing is pointless. Suggestion:
Increase dmg of stationary guns while increasing overheating speed as well. And: Get rid of that nonsense angle limitation.
My 2 cents.