I think one of the main problems is that, at its core, Arms is pretty much bland in regards to what it can be. Fury at least lets you play up the raging barbarian/berserker vibe and Protection has the stalwart defender theme. The heavy armor of the Warrior class also makes it to where Arms has to be more William Wallace than blademaster/Master Yi.
Arms just ends up being this weird amalgamation of "brutal strikes" without a general direction. They're trying to make that direction about vulnerabilities and Colossus Smash but in the process are making the spec fully dependent on Colossus Smash, It's at the point where you're just fishing for procs at the cost of everything else and go from crap to god based on if that stupid debuff is up. But moving emphasis away from the debuff pretty much pulls from the only thing that makes Arms even remotely unique.
I agree that removing Titan's Grip won't fix this at all.
I know you're well aware of the problems, but more just stating for discussion sake.