Because it implies that Batman can ONLY be defined as a tragic figure, when there's ample evidence that he's not.

He talks about being a tragic loner, but he's built a strong and loving family unit around himself over the years, moreso than any other single hero I can think of (We're talking soccer team sized numbers of sidekicks and allies). Yes, they argue and not everyone's speaking to everyone else all the time, but there's utter loyalty and love there too.

To suggest that he couldn't continue as Batman because he's married is just ridiculous. He's been able to operate just fine as a father all these years, why not a husband?