I propose adding an object-wide flag that can be set even for no-mod items (similar to the "for sale" bit and other status flags), which prevents textures from rendering as full bright. (This feature is misused so often that it would be nice to be able to disable it at the land level, too.)
Frankly, this is a plague on SL. Any time you have an area with multiple creators, somebody has to play the "full bright police" and nag everyone else to remove all the full bright items from their builds. Even worse, no-mod items are sold on the marketplace with full-bright textures. Why would any possibly want a glow-in-the-dark painting? Who knows! But people still sell no-mod artwork with full-bright textures, and when the item is photographed at precisely the right angle and time of day, there's no way to tell.
I get it: there are a few cases where you really do want full bright textures, like a light bulb, computer screen, or something else that produces its own light. But these are so rare that the majority of full-bright textures are just visual litter. They aren't wanted by the people seeing them, and in the no-mod case, they usually aren't wanted by people placing the objects either!