I would say that it amounts to the differences in two elements. First the amount of flex in the polymer absorbing at least a small bit of recoil and the higher bore axis redirecting recoil upward rather than rearward. It is one of those things, just like furniture or automobiles, where your idea of comfortable and mine may well be two entirely different things, no violations of physics required.
I have to agree the LCR does seem a bit easier to shoot than the J frame. My 442 and 60 both have a tad more felt recoil than the wife's LCR. Not a physics major, but I can feel a difference. All the same, I still prefer my airweight Jframe over the other little revolvers.