I guess what I'm going to say here is really a non-epiphany for anyone thinking about physics for any period of time, but as I think about it I am re-inspired by relativity. Relativity begins by insisting that the laws of nature be invariant under change in reference frame, whether inertial or not. It doesn't matter what induces change from one reference frame to another -- gravity, electro-weak, strong -- the invariance principles must apply, else the laws of physics are inconstant, or, non-'covariant' in the Einsteinian sense. So, while gravity stands out in that it induces an 'accelerated frame' for all masses in the area, the principle of relativity is almost a kind of theorem for all physical law, so that whatever causes a change in motion in an object also creates a context where relativity must be considered. In this regard then, relativity is logically prior. If acceleration didn't produce dilations and contractions, the laws of nature would be incomprehensible.
From this vantage point I can see Einstein's problem with nonlocality. Nonlocality allows the universe to routinely violate limitations on motion imposed by relativity. A great faith in the consistency of nature would lead one to look for a union between relativity and the other forces so that spooky-action-at-a-distance would somehow be reconciled with non-quantum effects.