It also prevents YOU from extending the product in some way, embedding it in your proprietary stuff, and then keeping the extensions you wrote secret from the rest of the world. Now, ME, I wouldn't be interested in keeping my extensions secret, because I don't really have anything to hide. But some folks, especially big companies, DO have something to hide. Perhaps, (not a real example) they mean to release a tablet with office software built in, but with a back-door built into the office software that allows it to secretly track all documents created and report back to the mother-ship. At least I HOPE that's not a real example.