You could script plain old vim in Lua long before NeoVim existed.
Lua is the only difference but it makes all the difference.
From my understanding, Lua is nicer than Vimscript, this means more people will create more interesting and better Lua plugins, that can only be used in neovim.
LuaJIT is also fast.
"Deliver a first-class Lua/LuaJIT scripting alternative to Vimscript." The rest seem fine but not really a reason to switch, and I don't know Lua so I'm not sure that's a reason either.
Is this the main reason? Are there other good reasons?