You're partly right. We get requests to support literally dozens of platforms and package managers, and Chocolatey is making things hard. It's also not something we get a lot of requests for, so it gets bumped to the back of the line behind... too many targets to list. We've considered just pulling the package.
The ZeroTIer Windows installer as it stands was not easy to build at all. It involved the use of a $1000+ product called Advanced Installer (the only installer maker that even came close to our needs) combined with weeks of developer time to put together a package. The MSI is designed to install on both 32 and 64 bit machines and to handle a huge variety of edge cases and Windows "spins."
We can look into silent installing drivers but as with absolutely everything else about Windows packaging I'm sure it's painful. Windows is by a huge margin the most painful platform to build an installer for unless your app is trivial. (Debian based Linux comes in second.)