While copy-pasta is an exceptionally dangerous form of code rot, I do agree that the ENTIRE point of good design is to emphasize code reuse. If you've ever come across a section of ugly code you have to fix, just because someone didn't feel like using Perl::DateTime, you know what I mean.
There are a lot of smart people out there. Most of them are smarter than me. (Think about the collective "smartness" of compiler developers every time people think the project should ignore compiler warnings.) I strive to stand on the shoulders of these giants as much as possible when writing code.