There is a certain kind of very influential academic who has a difficult time recognizing that they are no longer a rebellious figure courageously struggling against the tide of contemporary opinion, but rather have already successfully directed the tide along the path of their choice. Chomsky is one such academic, and Fodor is another.
Ortega y Gasset, in his generational theory of history, posited that at any given time in history, there are three generations, each with its own episteme and ethos. The oldest generation has been supplanted by the middle generation, which is the current dominant paradigm, but which is constantly being undermined by the youngest generation. It seems to me like this has always been the way things have worked in the history of ideas: each successive generation works to overcome and supplant its immediate predecessor, and once it has done so, it becomes the status quo. Sometimes, the middle generation has trouble letting go of its subversive attitude, as Jason noted in his comment. For instance, Noam Chomsky and others in his generation revolutionized the way we view the mind and human beings in general, and it must have been a big rush to do so. Now that their ideas have become the status quo, I imagine it's a bit of a let down. Of course, in many ways, and on many fronts, they are already being supplanted, so while they feel they are still they rebels, they are actually the target of new rebellions.
I wonder why it is that things tend to work out that way, particularly in intellectual spheres such as science and philosophy. I'm sure one reason is that it's easier to criticize than defend complex ideas, as any undergraduate who has written papers on famous philosophers has learned. Also, the best way to make a name for oneself is to supplant accepted ideas. However, I think the biggest reason for the constant flow of intellectual upheaval is that every system of ideas is flawed, and the people best equipped to notice the flaws in any system are those who are not fully invested in it. Someone (maybe Plank?) once remarked that the best way for a new theory to gain acceptance is for all of its detractors to die. That may be a bit extreme, but I think it captures this key aspect of the intellectual world: for new theories to gain prominence, the theories they have supplanted have to be widely questioned by those who have not spent their lives formulating and defending them.