Why stop at "cultural theft"? How about we try to figure out which land was first discovered by which ethnic group and return it all to those it was originally stolen from? I think they'd rather have wealth than trinkets. Generally when someone conquers a land they also get all the treasures that may be part of it, so at a minimum we should try to return those ill-gotten items to their true owners. The Islamic regime of present-day Egypt has pretty little continuity with Ancient Egypt where these treasures were produced.