we still need the AA filter for video or some fashion or portrait works.
I've been shooting a couple of D800Es, an A7R, a couple of 6Ds and an old 5D2 , and I know why Nikon did not go completely AA-less design with the D800E but decided to design special filter to eliminate the AA effect.
The A7R is indeed a bit (a tiny bit) sharper than the D800E at ISO50 -100 , but after that the D800E is actually sharper.
And , the A7R produces really annoyingly a lot of luminance moire that I have never seen or able to replicate with any of my other cameras.
so AA-less is only good for landscapers or nature shooters , it is really not good for any type of images including some artificial patterns.
and in case of the 24.3 mp FF sensor Nikon or Sony does not want to risk it with AA-less design , the RX-1R was a special exception designed for forum chart measurebators like some of us here(including myself).
personally, I could not resit trying it out my self for my kind of shooting and testing it out in real life and in my own lab (more like studio). but in real life, I never liked the RX1R due to its extreme moire, lack of proper AF , poor battery life and boring 35mm FOV, and I sold it just after a few hundred test shots I made with it.
the RX-1R was a great landscape camera if you need only 35mm boring FOV, but it did not work for me , I need proper EVF , proper AF and at least 25mm and 85mm FOV at which I shoot most.
anyway, the only real reason why manufactures go AA-less is that they want to save the cost of designing and developing actually good AA-filters , after all , the AA-filters (especially good ones used in the 1DX, the D4,the D800 ,or A99v,etc) are really expensive.