JackM: HA. I said Canon needs to do something special with a faster kit 18-55, so as to distinguish the Rebel line against Nikon and all the Mirrorless competition. Everyone said oh it can't be done. Fools!
This is a very different animal than a traditional DSLR lens.
The registration distance on the XF mount is 18mm, so any lens 18mm or longer doesn't need to be a retrofocus wide-angle, which makes the lens smaller, lighter, & cheaper. This is also the reason that Fuji's 18 & 35mm primes are so small, inexpensive, and sharp.
Pretty much any mirrorless or rangefinder mount has this advantage though, so hopefully more mfrs will follow Fuji's lead in releasing lots of nice small fast primes.