Romo is fun to watch. He plays the game to the absolute best he can and makes plays other QBs can only dream of. His attitude rubs off on his teammates who then respond by playing the absolute best they can -- whether on offense or defense. He's a fiery leader who inspires his team to believe they can always win and puts them in the right situation to do so. Like MBIII once said, "I play off Romo. Everybody plays off Romo".
Can't begin to imagine how other teams feel when they watch Romo play and see the Cowboys win. Most teams are conditioned to believe in each other and that their own QB will get the job done. But now entering last half of the season, many of those players realize the reality -- too many of them have QBs who can't get the job done. Some of these players would love it if Romo was their QB & others hate him cause he isn't but instead is the Cowboy QB. Who knows, maybe a couple of their good players who due to become FAs might just take a look at the Cowboys and think "maybe I'll check out playing there when this season is over". After all we can always use a few upgrades at some positions if the price is right. That's what Jerry Jones meant at Romo extension about other teams being interested when you got a good QB.