Empty folders in KSP directory

[orven]

I started to play KSP since 0.22 and I still have a question: those empty folders (internals, parts, plugin data, plugins, resources, sounds) - what are they for? I suspect that they have some use in the past (at least one of the mods I used had to be in plugins folder). And if it is so - why they were not deleted when they have no use anymore? Or are they automatically created by unity? Or maybe they are empty only when the game is not launched? Who can reveal the secrets of this empty folder mystery for me?

P.S. Sory if I am too annoying but I cannot get rid of my curiosity. And 1.0.3 hype.

[Kermunist]

Much of what is now in GameData used to be in these folders. In order to add (for example) a part through a mod, you had to put it in these folders along with the parts provided by Squad, and if you wanted to remove a mod you had to sort through and find all the parts that came with it. This was a pain in the neck, so Squad changed over to using GameData and subfolders therein. I think they also changed the format of certain key files at the same time. The old folders, along with the code to load things from them, were left in so that mods which hadn't been updated would still work. They've probably outlived their usefulness now though.

[Eric S]

What Kermunist said. The devs said that they'd remove the old folders at some point, and I thought that they'd be gone by 1.0, but apparently not.

[orven]

So one of my theories was right: they are just ghosts from the past.. But it's really odd that they've not been removed, even after so called release.