Hang on a minute - doesn't the AA filter actually serve a purpose other than just smudge our images? Doesn't it reduce moire and aliasing?
Indeed, that's why aa filter is spelled "anti-aliasing" :-)
Without it you would have to deal with that in post.
Probably yes, but the point is: only if required and only in that particular area! And moiré effects on full res stills should be very far in between, maybe 1% of shots in 10% of the image?, that means that for the others you're getting sub-optimal stills because the moiré effect in video is much more ubiquitous.
With your argument Canon could also force the camera to apply all other image "enhancements" to raw like lens profiles, de-vignetting, CA correction, nice poppy colors, ... but also all at the cost that if you don't want these in post you cannot get rid of them. If you shoot raw it should be as raw as possible, postprocessing software is always better at doing the job, even if more time and work consuming.