I agree size is a factor, but the 28/1.8 is fairly small making an alternative to the fairly chunky and expensive 24L and 35L (this was my logic for getting it). I just hope they don't retire the 28/1.8 etc.
Clearly adding IS to a f1.8 would make the front element huge. However, digital bodies, even the smaller crop ones, are quite big compared to the old FD film bodies, so below a certain limit it's probably not that important.
Presumably this is also why the 24-70 II does not have IS (I seem to remember this being a wish list for some), but price wise it would have been easier to absorb.
Most people want a prime to be fast though, specially in this focal length range. I just don't see the application however for these quite expensive f2.8 primes. Video perhaps.
even for video, giving up all that light..... well that sucks. Might as well get a cheap crop and slap on a 17-50 sigma with OS.



