Especially if women want equality. Otherwise it goes a bit like this: I want equal opportunity to get into the same job as you (male), but I don't want to have the same accountability as you because I'm a woman. This is a totally irrational form of anything and it should be dealt with harshly. A side note, if you have the above expectation, then you are actually sexist. Indirectly, but still sexist.
Imagine of the Batman employed lethal methods against all the people he fought.
1) The bodies would begin to pile up, and so would the questions of the people. "Is he really a good man? Can we trust him?" Batman's not killing gives him a much better image for the people of Gotham to look up to and trust in. Batman wants to inspire people, and killing people sets a bad example.
2) Batman is already taking the law into his own hands. If he takes life into his own hands, where does that end? Sure, it'll start with killing the Joker for instance, but after one act, the following will become easier, and so will finding justifications for doing so.
3) Bruce Wayne knows the pent up demons inside of him that he lets loose when he's Batman. If Bruce thinks refraining from letting those demons kill, then we can't fault that.
Yes, Batman's one rule is a good idea, because it is a sign that he is acting honorably when he is carrying out his work. Batman is doing a good job trying to help other people, and his one rule is a good rule to make sure that his powers are being used for good.
People usualy say he will be no better then the criminals he faces if he kills, but that is not true, unless you think everyone is innocent, you can always rest assured batman kills no innocents.
About inspiring people and having a good image, i'm sorry, but he can't scare criminals that know he will not kill them, and if you point out that he beats them half to death, then, he is not such a good image after all right? That is downright torturing the criminals.
At least there is the death penalty someplaces, but nowhere will torture be within the law.
Bottom line, either he has a good image or he is an efficient crime-fighter. And if it's all about inspiring people, he really should be something else, like a political activist, not a vigilante.
I believe batman doesn't kill because he needs something to stand out when he says he is no criminal, even though he really is, and in his insane little mind where his parents' deaths are the worst thing to ever happen, the only thing that can do the job is the no-killing rule.
I mean, in the dark knight, if he had just run down the joker rather than just dithering at the end, a lot of awful things never would have happened, like the debacle at the hospital. If I were Batman, I would have made sure that the Joker had really suffered and then died.