You, sir, are a perfect example of why The Miz is a great US champion.
You hate him because he doesn't defend the title. You think a title is supposed to have honor and prestige, but it's just a prop. Miz having it and barely defending it (on TV) pisses people off. It's doing a great job of getting him over as a hated heel with the audience, and he gets some of the most negative reactions out there.
It's not about defending the belt; it's what holding a belt can do for a wrestler.
Maybe the state of the titles in the WWE has dropped so far that people like you think that the purpose of the title is to solely add prestige to the wrestler and further him/her as a face or heel. That just isn't the case. What a title should be is the reward of being the best in a certain division (main event, midcard, etc), not something to get someone over. Just take a look at Drew McIntyre. Giving him the IC title did nothing to get him over, and he only started to get a reaction out of the crowd when he had his feud with Teddy Long.
To further what me and topic starter are saying, let me ask you a question - why should I care about the United States title right now? Is there currently a feud involving someone challenging the Miz for his title? No. Have there been any matches recently for the title itself, or for the right to fight the champion? Not at all. Then what purpose does the belt serve (other than a prop, as you say) if it isn't being involved in storylines or being put up for grabs? If the belts in professional wrestling are just "props," then why should the United States title matter at all? Why do people in the IWC complain all the time the midcard is dead in the WWE? Because the titles are being given out as "props" by the WWE to wrestlers in an attempt to get them over, but if the belt doesn't have any prestige, then how do you plan for it to get them over?
In the 90s, it could be argued that the IC title was the most prestigious title in the WWF. Sure there was the WWF title itself, but those matches were almost never as good as the IC title fights. You'd have guys like Warrior or Hogan go out and win a 4 minute match and retain the title, whereas you'd have guys like HBK, Ramon, Perfect, and Bret Hart go out and fight 20 minutes in a great match for the IC title. It meant something to hold the title because you knew if someone held the belt, he had earned it. You can't get someone over with the belt, as you claim, without making sure the fans care about it first. And right now, I'd bet you couldn't find a person in the audience or on here who even cares that the Miz has the United States championship.