Just my opinion, but I do think it's a bit DYKWIA when I see people walking around with their Silver and Gold tags on their bags.
I tend to agree with you on bags that people are taking on board, but I still do put my gold tags on hold baggage. My reasoning (hope really) is that they will actually come out on baggage claim faster and I wont have to wait long to leave the airport after the flight! I know crazy!