Anyone worth their salt as a programmer will tell you that programming by cut-and-paste is always, always, always a mistake. You might do it for expedience, because reworking whatever you're cutting-and-pasting to be more generic might take longer than you have to deliver your result, but there is never a situation where it's a good thing.
But the subtext language has a demo that posits the question what if your language was built to handle all the issues for you?.
I don't think I'll be programming in in any time soon, but its always interesting when a new idea comes around.