I feel like squeezing out every possible place for people to be creative and express themselves creates a pretty boring environment. Like, imagine if all buildings were just purely functional. They'd all be the same grey box shaped things. I recently worked on a codebase that was lovingly developed by a single maintainer and had all kinds of weird and wonderful quirks that made me smile every so often. I'm a pretty serious person most of the time but I'm not going to lie it made my day that little bit more interesting.