The problem here is there are two very different visions of what COH is and should be. At one point or another the devs are going to have to take a stand on it as we move forward.
I'm not sure there is anyway they can get around this.
As for the binary mez system, yeah I . . . don't know what to say about that. Except the following:
Should mez matter in the game? Or shouldn't it? If the answer is it should, then some would argue it should matter for EVERYONE, equally. I'm not sure I agree with that argument, but changing it at this point would be a changing a fundamental design philosophy that makes the game what it is, as you say.
I guess the question I would have for the original COH devs if they were available is: (Though I agree that it may not be fair to expect the HC devs, or the devs of ANY other sever for that matter, to answer that.)
Why is it okay that some ATs have to worry about mez, and some pretty much don't?