Canon Rumors said:
While the EF 85mm f/1.8 IS would be a welcomed update in the Canon lineup, the EF-S 22mm f/2 STM is a bit odd, considering there’s already an EF 24mm f/2.8 STM in the lineup.
What in the world???
The whole reason the 24/2.8 is (to me) useless is that it's not faster than f/2.8. I'd rather have the 17-55/2.8 IS for crop or any of the 24-70/2.8s for full-frame.
For me, the whole point of a prime is SPEED. Unusual focal lengths (like my 2800mm/10 telescope) and/or features (like the TS-e lenses) can be good too, but zooms are now plenty good optically so primes are of no use if they just overlap with zooms. A 22/2 for crop SLRs would be incredibly useful - way more useful than a 24/2.8 which is overlapped by multiple zooms.
Of course, for me, this is all moot since I got the Sigma 18-35/1.8. 8) 8) 8)