Why so many complaints about no external recording on the 5D Mark lll?
Because people are never satisfied.
Those "budding filmmakers" who had to put up with a crappy home-video recorder (or shell out thousands for professional equipment) a few years ago, then got a "cheap" 5D2 with all the wonderful EF lenses suddenly realised how good they could have it for IQ, ISO, DOF.
But somehow, after 4 years, that's not good enough anymore. Considering we're at the point where anything shot is "good enough" in the eyes of Joe Moviegoer, the difference in dropping a bit or two of resolution is going to mean diddly squat.
And that's not even taking into account that 80% (conservative, probably closer to 98% or higher) of people who buy 5D3+d800 combined are going to use it for photos and home-movies and never watch it on a colour-calibrated TV screen or 3m+ screen.
(one day people might realise that a good script costs nothing, and will bring in more people than an extra bit of colour detail...)
This is the internet, we got whingers...