Doing bathroom remodel I notice incoming bare grounding wires of standard 3-wire cable (12ga black, white, bare) is not connected to green screws or green grounding wires supplied with the fixtures, just hanging loose or pushed back in the box. Doing a quick check, I find the same lack of grounding connection at several other fixtures (ceiling light, outdoor porch light, etc), although I haven't checked all of them. In one case, the incoming bare wire is cut back to the insulation and not even available for connection, apparently not used on purpose.
This seems like a no-brainer safety feature to me, and requires such a trivial amount of extra effort, I'm beginning to wonder if I'm missing something. Is there ever a reason NOT to connect the bare grounding wires?