No one else seems interested in writing them here and my boss doesn't want them because it will take to long to go back and add them for existing code.
I know that they will help improve the quality and testability of the code that I write though, so I've started creating them. I'm thinking of it as part of a new year motivation to write better code and improve my overall productivity.
Hopefully everyone else will see the benefit and start join in.
No, I'm not going to go and add them in for existing code. At least not until I have reason to go and do something else with that code.