Why not?

I the configuration.nix of NixOS is a nice, small way to get your dev machines configured and installed with the stuff you like. Just copy it on your new machine and off you go :)

I don't know if I would ever use Nix instead of the more language specific packet managers.

Nix derivation and nix store managed artifacts is a superior model to many language specific package managers (though the learning curve is non-trivial), we use it with Haskell extensively, for instance.

I can't wait for someone to write a great book on Nix. I was so lost in it. I had it running on my home server, and needing to compile my own things because of what Nixpkgs lacked was a constant struggle.

It was a very frustrating experience. A frustration which was led by the fact that i could tell how powerful Nixos was - if only i could grok it.

Yeah a book on nixos would be valuable I think. Understanding nixos really comes down to reading all the docs then trying to accomplish what you need to do, learning by doing and reading source code.

I love nix, my biggest gripe would be that the Nix language is dynamically typed...

This is actually a good idea, they complement each other nicely.

No. They do not. Docker wants to manage containers but nix wants them in the store. I went so far as writing a derivation and tool for pulling a container into the nix store without docker so it could be docker loaded.

I really don't like docker.

At the very least Nix would make your Docker builds more reliable. Granted, you could then start making arguments for "why use Docker at all", but i can't answer that.