What you say ("The whole point of choosing a permissive license is that you want others to have the right to profit off of your work and give you nothing in return.") is obvious in hindsight, and should go without saying if you start a project with the express intent of commercializing it. However, in many cases, it's not the obvious decision for reasons related to the project's genesis (e.g. Spark or Mesos being student projects), and in others, it's not the route taken because of an idealistic impulse that I think would be really unfortunate to see squashed.