Copying and modifying is a sensible way to learn. Doesn't mean you should ever pass it off as your own, but there's value in understanding how something else works by poking at it. Then throw it away and write your own, or find an appropriate Open Source project to work from.
I do agree that it is a sensible way to learn, just that they shouldn't take credit for it. I totally don't mind poking into stuff, it just means the original work is awesome and there're stuff to learn from it. However, there's always been the problem of taking credit away from the original creators, acting like its all yours to begin with.
