I agree that there is no uncanny valley, but I believe that critics' complaints (and perhaps your own) stem not from independent comparisons of both 24 and 48 FPS to some ideal format, but rather from an assumption that 24 FPS
is the ideal form.
If you believe that the purpose of a film format is simply to convey moving images to the viewer with as much fidelity and control as possible, as I do, then 48 FPS is objectively better (and 96 FPS would be better still, although there are obviously diminishing returns). The other opinion, which is that 24 FPS has some inherent artistic merit that makes it the ideal format for cinema, is bizarre and incomprehensible to me, and that type of argument could be (and probably was) used to argue against audio ("talkies"), color, surround sound, digital color correction, etc.
I saw The Hobbit both in 3D HFR (digital projection) and 3D IMAX ("real" IMAX, 70mm film projection, in 24 FPS). The difference in fidelity to me was smack-in-the-face obvious. HFR just looks so much better. In 24 FPS, the strobing in any shot with camera movement is so bad that it feels more like a camera or projector malfunction than a format that some people genuinely prefer for artistic reasons.
I definitely hope HFR is the future of cinema, just like I hope high resolution LCD displays become even more widespread, cell broadband networks get faster, digital cameras get better and higher resolution sensors, etc. I believe all these things are strictly better. To me, arguing that 24 FPS is better than 48 FPS is as bizarre as arguing that everyone should still use dial-up Internet just for the experience and so they will not take the wonder of the Internet for granted.