The truly good student is the one who signs up for the class with the goal of mastering the material being taught as well as possible. The 'good' student in this example cares more about gaming the signaling mechanism than actually learning the material - this is why he'll spend his time arguing with the TA over a handful of points on his problem set than spending that time going over the material again. The 'cynical bad' student is already convinced that he's not going to get anything out of the class, in which case he either 1). is taking the class because he has to or 2). is a fool who should be taking a class better serving his needs and not wasting his time.
Also, I don't know much about philosophy (and I suspect this is far less applicable for philosophy), but in science and engineering often mastery and innovation in a field requires an extremely narrow focus that, in turn, requires a significant investment in time and resources. This includes transmission of specialist knowledge to graduate students and postdocs, grant writing, paper publishing, acquisition of equipment or access to equipment. So I don't really think it's entirely fair to chalk up lack of interdisciplinary interest and/or innovative methodology predominantly to a system that weeds out people not willing to think the way it wants them to. (Not saying that tenure doesn't have its own problems...)
The 'good' student belives that the signaling mechanism and the understanding of the material is the same thing, they're identical. For those students nothing exists beyond (the signals of) good marks. So in a way they don't really game.
I'm engaged to a "good student". She was damn well and fully aware, her entire life, that the signalling mechanism is very different from actually learning useful material.
As a two grad-student couple, we have mutual academic envy. I envy that she finds it easy to memorize large sums of material and pander to the system. She envies that I find it easy to acquire an intuition for the material I really care about. I envy that she's "saving the world" as an ecologist. She envies that I can make a good living out of my field.