First off, I don't think it's a good idea to have resolution, sound and such options in a Lua file, so it is required anyway.
And it is easier to edit a single configuration file than to go around and hunt for Lua globals and other places where the settings are. Like
SPAWN_INTERVAL variable that is hanging out in some random Lua file.
EDIT: and I think some people have said that they were scared of editing a Lua file, because that would be "programming and too hard", or something like that.