You shouldn't feel compelled to switch, Nvim is intentionally user-compatible with Vim.
But these days it also makes sense to ask instead "why should I use Vim?" The version of Vim that you actually use probably wasn't installed by default on your main development system. So installing Nvim is the same as upgrading Vim.
He literally asked several times for reasons to switch to nvim, but your answer basically amounts to "well because it's not hard". Telling him upgrading is not hard, or that it is compatible with vim gives him nothing.
From the nvim GitHub page:
Modern GUIs
API access from any language including clojure, lisp, go, haskell, lua, javascript, perl, python, ruby, rust.
Embedded, scriptable terminal emulator
Asynchronous job control
Shared data (shada) among multiple editor instances
XDG base directories support
Compatible with most Vim plugins, including Ruby and Python plugins.
What do you use as your main development system? I'm on an Arch Linux VM, so I have an up-to-date Vim 8.0.
And since Vim 8.0 does terminals and asynchronous jobs now, I don't see much value for Neovim unless you have an IDE that integrates Neovim via its API.
> unless you have an IDE that integrates Neovim via its API.
This will be the biggest win for Neovim. When something like pycharm/webstorm vim support is moved to real vim rather than a reimplementation I will change.
I tried NVim maybe 2 years ago. At this time it wasn't able to read my complete .vimrc. So that was a huge show stopper. Does that work now and can I be sure that nvim creates the same setup based on my rc file?
But these days it also makes sense to ask instead "why should I use Vim?" The version of Vim that you actually use probably wasn't installed by default on your main development system. So installing Nvim is the same as upgrading Vim.