Its the same reason makeup is aesthetically better. Makeup for actors and normals alike are a way of blending out imperfections to regress to a norm. We actually find the average more beautiful than the eccentric when it comes to the human figure. 24fps and motion blur also blends out imperfections, but filming imperfections. With HFR, you feel like you're watching someone being filmed as it becomes too obvious that there's a camera involved due to movement imperfections/etc. That' a 4th wall violation and takes away from immersion.
When you remember someone's face, do you remember every freckle, mole, shade, and strand of hair? If you were to draw it on a paper, wouldn't it look closer to a drawing than a realistic representation? That's whats going on here. Movies with their theatrical effects are tapping into that, so its like you're watching a memory. You make it too real feeling or present 4th wall realizations and you remove the suspension of disbeleif.
All that said, 24fps has its limitations. Transformers was where I found this most obvious, they had to do all the transformations in slowmo for you to actually catch what was going on, and even then it was still too overwhelming to catch without the extra frames. I think HFR will be more successful if they add in some effects to reduce the obviousness that its being shot by a camera. What they are/will be, I don't know. I think camera stability, shooting angles, scene switching, and motion blur all need to be reworked for it to look a lot better. That's a tall order and its gonna take some time.