Well, the franchise already has the Doctor for doing the fluffy pacifism thing - he won't get his hands dirty and he won't hang around to deal with any consequences. Jack, however, is another matter entirely and we've seen on both shows that he'll do whatever is necessary to achieve the desired ends. It's not always nice and it's not always clean, but sometimes it just needs doing... and sometimes, as a writer, it's more interesting to just follow things through than to try to find ways to avoid them! :) Jack is very much Captain Pragmatic and smart (and a little warped) with it, which is a fun combination to play with.