If you can run Skyrim on Medium or higher, it doesn't matter. it doesn't really improve that much. theres a difference, but it's pretty small.
If you can't run Skyrim on Medium or higher, it also doesn't matter, because they will break your game.
I think the main reason they were released (besides "because we can") is so that modders could remix them and then downscale to the normal sizes, which gives better quality images than trying to manipulate an image that's already been set to the scale you will be using and may well also have some lossy compression.