From having seen the FB discussion, the idea from the users was to have the "Create LightMix Automatically" but have it work for only certain lights - this would be in place of manually creating the LightSelects, or using the current Automatic method then deleting lots of LightSelects (concept was you have 200 lights in the scene, but only want LightMix for 5 of them). I have no idea what the selection process would look like for choosing the lights, though :)