He can't be a household name because he doesn't respect the house, house occupants, house rules and house leader and his disrespect is the main reason he is talked about a lot. Do you see Matt Serra as a household name, inspite he is a former champion and a cool dude?
Nick is a good fighter at the best, but UFC as an institution is rooting against him for the reasons exposed. So how he could be UFC household name even if he beats GSP? How to replace someone like GSP, a noble fighter and UFC poster boy for Dick Niaz?
You've turned this into a business discussion now. I couldn't care less if Diaz does what he is told or not. I couldn't care less if he doesn't "respect the household". I'm a fight fan. I leave the business side of things to the businessmen.
And I personally thing anyone on the planet holding at UFC title at that moment in time is a household name in MMA. Matt Serra was everywhere in the MMA world for KOing GSP. He might not be a household name now but by the same logic, neither is Royce Gracie. Demetrious Johnson would probably be the least popular current UFC Champion, but if he hadn't lost to Dominic Cruz, and wanted to move up and fight himm I'd consider that to be a big champion Vs champion super fight.