Neilyb wrote in post #15008622
Because Nikon do not seem to have a problem doing so.

Then one should buy a Nikon instead of a Canon.
Pretty silly really anyway because built in flashes suck. They are underpowered, in the worst possible place for redeye and ugly shadows, rob power from the camera itself, and are only a marginally useful way to do wireless off-camera flash control (due to obnoxious white light flashes, limited reach and overheating).
I can count on one hand the number of times I've used a built-in flash in the past ten years, taking over a million images with various Canon cameras that have built-in flashes. I'd rather use a small, accessory flash than the one in the camera and keep wishing Canon would leave the built in flash off crop models, too, but that ain't going to happen.
One of the design goals of the 6D was to make a more compact full frame camera. The pentaprism in a full frame camera needs to be bigger than in a crop camera, so addiing a flash on top of that would have made the camera even larger. I applaud Canon's decision. I do wish they'd put an articulated rear LCD screen on the 6D, 60D/T4i style... Wish they had gone with CF instead of SD memory too... And really don't care about built-in WiFi, would never use the built-in GPS (unless it can help be if I get lost).... But those are entirely different subject.