Short answer: Because the change breaks a lot of code for no reason other than a stylistic one. It wouldn't be difficult for it to be a function, but the interp

Short answer: Because the change breaks a lot of code for no reason other than a stylistic one. It wouldn't be difficult for it to be a function, but the interpreter to allow the old invocation. Though it does serve as a neat diagnostic "this program wasn't built with python3 in mind" message when you encounter the syntax error, so maybe it balances out...