You should know that Houston itself has a problem with turnouts. For club racing, I usually have to bring my 8th scale, 10th nitro and 10th electric just to have a good chance at racing something.
GT was a new class last year I believe and had a total of 5 entries between spec and open which isn't bad but doesn't make me want to spend the money to buy one.
Sedan had 35 entries (this is total, not at a single race, not everyone travels)
8th scale had 23.
The two major "popular" classes only had 5 or 6 race participation from only a few people.
Nice find and 2wd 8th scale would be entertaining, as would electric 8th scale which I believe is below in one of the pictures you posted but I just don't see it right now. Sorry man. I could be completely wrong though, perhaps everyone wants to drop a grand to have another car. I personally have 6 that I actively race already (well when some can be, offroad is always good to go) and then another 7 that sit around 100% of the time like 12th scale, 18th and miniz.
Plus, every time a spec class gets popular then people start cheating and higher level drivers get involved which is basically cheating to most sportsmen level drivers. I've seen it many times over the years and then the class usually dies off. 8th scale 4wd is near that point, probably because of engine costs and probably because of tire costs but for 6 times a year like the SW series it isn't that bad for some that attended most of the SW series.