We strongly prefer automated code checking in all extensions deployed on Wikimedia wikis (T929), we encourage certain linters, we even mandate test entry points.
The BoilerPlate extension should reflect our consensus for this. It's a dozen extra files and directories, but anyone looking at extensions in use on WMF wikis will be exposed to them. And easy automation of best practices helps development of every extension.
We could put other best practices in BoilerPlate, see T97105: BoilerPlate extension should show latest coding practices.