Because I wanted cheap white tires, and the CSTs came in 23mm for $19 or so per tire. I'm not sure why nearly every other SSFG rider in L.A. does so as well though. Probably because they're cheaper, perceived to be faster or maybe, as with anything SSFG related, it's just the aesthetics.

Not having seen anyone here, except for a handful of older commuters, express any interest in tires wider than 25mm for their singlespeeds or fixies, a $49.95 28mm tire sounded like the SSFG version of "Jump to Conclusions", which is why I questioned the market for these tires as a company's sole product.