Not a luthier, but did study mechanical engineering. Holes or cutouts would reduce the weight of course, and is old hat in many types of construction (like airplanes, actual bridges, etc.). But if that had been my intention, I might have made the bridge thicker than usual to compensate, and I'd have to consider if, and how, the size and arrangement of those holes would affect the rigidity of the bridge overall. I might consider scalloping the wings-- parallel to the strings, but with none of the grooves going all the way back to front, probably starting at the back, each groove going a bit past the centerline, and not too close together. I'm sure I've seen something like that on guitar bridges. Could smooth out to waves rather than grooves, if you really enjoy sanding.
Wow, though! This question made me reconsider the curvy bridges on some antique guitars. I used to think this was a purely ornamental flourish, but of course these curvy shapes are lighter than rectangular slabs would be for a given footprint, without giving up too much rigidity, especially front-to-back. And the way many of them were shaped now look to me like clever ways to taper rigidity toward the ends while losing more weight than a simple taper, and an opportunity to show off at the same time. Am I crazy?