I use them out of courtesy, to notice the person in front of the content that said content is (c) and that I actually did not forget to set a BSD/MIT/GPL/CC license, and/or to link to the actual license (which indeed leverages copyright).
Of course I know this is not needed from a legal PoV but I'm not using it for legal protection, I'm using it for actual humans to parse.
Also, the date metadata has been useful to me a few times. Please don't increment it automatically.
I do it for all three reasons, but habit most of all.
But thanks for the links. There also seem to be (other?) lawyers on this comment thread who have pointed out how useless such notices are for enforceable copyright protection.
I use them out of courtesy, to notice the person in front of the content that said content is (c) and that I actually did not forget to set a BSD/MIT/GPL/CC license, and/or to link to the actual license (which indeed leverages copyright).
Of course I know this is not needed from a legal PoV but I'm not using it for legal protection, I'm using it for actual humans to parse.
Also, the date metadata has been useful to me a few times. Please don't increment it automatically.