The DSLR market as it is today really doesnt depend on the average Joe if you ask me, the average Joe was happy with his compact and is now probabley happy with his camera phone so never bothered with a DSLR in the first place.
Go to any major vacation destination and it will blow your mind how wrong you are. There are usually as many, if not more, users with a DSLR than there are with a compact camera. And its only going to be more true as people aren't gonna supplement their iPhone with a P+S camera, they'll supplement it with a m4/3 camera or a DSLR. Now, many of them are wasting the potential of a DSLR, by putting a super-zoom on the front, never learning settings, and using it like a P+S; but without those users, DSLR's would cost 2-3x what they do.
Canon would never had considered things like a touch-screen if they didn't care what the average joe was used to.
Canon should also make a 30mm f2.8 EF-S for the Rebel. That will really make the Rebel close to the size of some "interchangeable lens mirrorless". Both will have much better Ergonomics than any mirrorless.
Even then, the body of those mirrorless cameras are still half the size of a rebel. An NEX with a pancake lens can fit in your jacket pocket; a T4i with the 40mm probably can't, at least not conveniently.
It makes it smaller, which is nice, but the very nature of the EF mount means that Canon's DSLRs aren't gonna match the small size of a mirrorless. But, as you pointed out, ergonomics are the trade-off for having a small camera