I agree and disagree... I agree wholeheartedly that the reason the SA mount hasn't sold at all is that the bodies haven't been compelling, and that if these bodies were really compelling, the lenses would start to move.
The caveat to this is that the SA line is already thought of by dealers as a failure, and that is a large and complex line to stock, with many overlapping lenses (Sigma bolts an SA mount on anything they make in Canon and Nikon mounts - at least in theory -I suspect there are a few that have NEVER SOLD A COPY (300-800 f5.6 zoom anyone? It's theoretically available in SA mount, but at $8000 and limited production even in Canon and Nikon mounts, is the only SA version in existence one that Sigma takes to trade shows?)). Nobody's going to stock that 300-800 (or worse yet, the $26,000 200-500mm f2.8, also supposedly made in SA-mount), but how's a dealer to choose between an 18-200,18-250 and 18-300? Equally confusingly, there's a 17-50 and a 17-70, plus an 8-16,10-20 and 12-24 and two separate 150-600 lenses (plus a 50-500). Only a few primes are available (although some of those are the desirable ART lenses)...
The SA mount itself turns out to be an odd hybrid - it's pretty much a Pentax K bayonet, but with the flange focal distance and electronic contacts of a Canon EF mount. My guess is that an SA mount lens is actually an EF lens, with the SA mount plate bolted on at the last second (if you swap the mount plate from a SA lens onto a Canon lens, it'll mount to a Sigma body, and everything except image stabilization will work). Sigma probably doesn't really stock many of the lenses supposedly available in SA - they just put a plate on an EF version that's made in quantity when someone orders one...
When Fuji introduced a new lens line incompatible with anyone else, they presented dealers with only three (four rather quickly, when the zoom hit) lenses to stock, and the lenses were well chosen to complement the bodies. There are now 20+ lenses, but there are also a million bodies out there to put them on, with a couple hundred thousand added every year. If you're a dealer wanting to stock the new SA bodies, you have to choose from an array of lenses to carry, and you may not make the same selections your customers do... I suspect many will just carry the 17-70 Contemporary as a "kit lens", and say "anything else is special order, although there's quite a bit to choose from". Any other strategy involves stocking lenses that may well not sell.