Thanks for your interesting comment.

I agree with Roko that commercial lawyers collectively do some good. Things are less clear at the margin. I know very little about the world of commercial law and you're probably in a better position to judge than I am. Still, two brains are better than one. We should talk in person - I'll be in San Francisco starting December 18th.

I find the tasks and people associated with those firms obnoxious

This seems like a potentially compelling reason for you to eschew a profit maximizing job as a lawyer even from an altruistic point of view. My observation has been that people tend to underestimate the difficulty of sustaining employment at a job that they find unpleasant.