Them wanting to make more profit on a remake doesn't mean we can't or won't complain about it or that the complaints are unjustified. OOT3D sold over 3m units globally, at full price, and would have been much cheaper to develop than say a new Mario title or ALBW. There's room to cater to the most loyal MM fans.
AFAIK OOT3D was very well received even by purists.
Like I said, I don't know why they didn't include it, just pointing out that the implication that it was easy might not be accurate.
Again with remakes or even remasters there's absolutely no way you can please everyone so that's why we should be grateful the original is still available. There was certainly complaining about OoT3D's new look as well.