Why no FF equiv. to EF-S 17-55/2.8?

MAC wrote:

well, I'll give you my strategy.

keep the modern crop camera for reach and zooms (eg your 17-55 IS and the 70-200 F2.8L)

budget for the 5d3 or 6d with a few of those primes I mentioned -- for me the 100L and the 35 f1.4 or 35 f2 IS (eventually)

now you have multiple fovs with the great primes by keeping both formats

and the zooms on crop are very good

you see once you are f2.8 and start stopping down, the two formats get closer to equal in IQ

but it is the primes f1.2- f2.8 that sing on FF