It WOULD work if he was a creator owned character.
If Batman was like Hellboy, there would be a beggining, development and an end.
His vilain would have "resilutions".
So you would have the opportunity of some of them, like Harly, Two Faces, Clayface, Bane, Penguin AND Riddler getting better or changing sides or good.
All of the guys that I mentioned above had a anti-hero or actually heroic phase, or got better at some point. Did it stuck? Obviously not.
What causes the problem is that you have always to use the same vilains again, again and again on company owned comics.
If the choices that Batman did had any real impact in universe, his no kill rule would make more sense, and showing mercy to guys that can recover could be rewarded.
Thing is, this would never work because the way that the comics MUST work, but Bruce has no idea about it.