Seriously though, The main reason for postulating gravitational waves is that Einstein was staunchly against the idea of nonlocal interactions, i.e., “spooky actions at a distance” as he called them. He insisted that nothing can move faster than the speed of light, including gravity and EM waves.
But now we realize that Einstein was wrong about the spookiness of quantum physics.
Excellent point. The world has been looking for gravitational waves since at least the mid-50's. Robert Forward (Hughes Research Labs) built one of those big aluminum cylinder detectors that he housed in the UCLA Engineering building in that time-frame. Others may have preceded him.
That's a long time to look with ZERO results. If we have a theory of gravitational waves then we should have some idea of the magnitude of the phenomenon. If so then the requirements for detection should also be calculable. I'm no expert but your thought that maybe Einstein was wrong is sounding more and more like Occam's best guess.