I think a big reason you don't see purple belt innovators anymore is because America has a lot of homegrown blackbelts now. Before, not only were their not many, but many people believed that getting a blackbelt was unobtainable for most people.
Now that it's becoming clear that anyone can be a blackbelt someday, and the fact that many blackbelts are starting to put a lot of information on the interwebz, there are not so many purples who have to pick up the slack. Aesopian was doing something that many people weren't doing, and that was putting up well thought out BJJ concepts on the internet. "Most" people accepted that he was doing it as a purple because there weren't other people doing it.
Now there are, so there is no need for purple belt instructionals these days.