You are right again.Therefore the EF-S 35mm can be made better than a 35mm EF.
Can be. But will it be? Canon may very likely sacrifice IQ to keep cost low (Nikon's 35mm f/1.8 DX is $200). The current 35mm f/2 on APS-C is optically better than the 18-55mm f/3.5-5.6 IS kit lens, and actually delivers IQ similar to the excellent 85mm f/1.8. How much optical improvement do you expect from there?
The main complaints about the 35mm f/2 are that the build quality is poor, no USM, etc., and if they release an EF-S version of the lens, I doubt the build quality will be all that much better (assuming their target market is similar to Nikon's for that lens, they'll price it accordingly, and it will end up with build quality closer to the 18-55mm kit lens than to the 60mm macro).
May be Canon marketing have an idea that people like to think " Mine is bigger than yours". So APS-C user are forced EF prime lenses. For the deep pockets they go for BIG prime L lenses. For none deep pocket, they use non-L prime lenses.
Unfortunately, I am from a slightly old school . I like it small and good. That is why I am longing for good EF-S prime. As for the pricing, If the 7D user will spend $1600 on the body only, I am sure that they would not mind to pay for a EF-S good prime (optically and true USM) with the price close to the L lenses with smaller size and weight.
I know, I am the minority.