Now that I have re-visited the AW page, I see the rapid known as "fear and loathing," and concede that it may be a must-run, though it is easily scoutable and it did not occur to me to portage it. The rapid was class IV at 800cfs at Roger's Crossing and I sent everyone through it on beta. One person had a brush with the island rock, no big deal, not hazardous IMO. While most rapids look bigger at river level than from the road, the ledge at the large island rock only drops about 3 feet.
I also see that the run is not known as "fear and loathing" at all, but "horseshoe bend" for the dramatic Z-turn the canyon makes. The confusion lies in that this is also the name of a bend and section on the San Joaquin. I think people took to calling it by the rapid name to clarify.
This rapid name combined with the power of suggestion and, as you said, "lack of information" must have deterred people because, as you've pointed out, people do not often do this run. I feel like it is a run that goes at the very end of the season when people think everything's over and done with, and it's a great run that could be enjoyed by more boaters. I don't feel the need to proliferate tweets about how great it is or how great one is for doing it, I just think it deserves a fair representation on the radar screen, which I guess it already has if you don't read into it too much.