Bruce was way too good for Barbara and that's that.
When I was young, 14-15, I had a huge crush on my piano teacher who was in his early 30's. He had a poor temper, but he could do no wrong in my eyes. But to actually go out with him when I turn 18 would be wrong on so many levels. He was friends with my parents too, and well--you get the parallel.
Barbara Gordon was about 18 and Bruce was 35+. She's Commissioner Gordon's daughter, batGIRL, and she's a kid. Bruce is like her uncle. I'll never understand why the writers pushed that angle so much in the DCAU.
The only way I can see them getting together is if Bruce was 60 and Babs was 40, and they've grown lonely. Even then, it would be more companionship than love.
Dick and Babs were perfect for each other, and the writers somehow didn't want to tap into that. Instead, they fabricate this pedophilish relationship btwn Bruce and Babs and it was awkward as hell to watch.