Isn't this more of a debate about whether plugin/theme editing should be allowed at all? It's already allowed by default and this plugin seems to improve on that, not make it worse.

So from what I can see, the plugin is a suitable candidate for inclusion (assuming it is good code - I haven't looked), but only if we continue allowing the code editors.

I've never thought including code editors in core was a good idea. I've only seen that causing carnage, not solving any problems. But if it's going to be there, then it may as well be made useful via a code revision system.