Screenshots of what you're doing.

I don't personally see why the GUI has to be any more complicated than this:

That's not simple, that's simplistic and unfunctional. The directory needs at least to be editable from the keyboard :-P

The 'destination file' paradigm needs to be removed anyway, since it is confusing. (IMPORT from destination???)

That's agreed already - I'll remove it.

The 'redetect' button doesn't make sense, unless i'm confused as to its function. If you change the location of the file while the application is open, wouldn't you just browse for it again?

it for this scenario:
- the app enables/disables buttons and checkboxes based on the files that it finds in the xonotic user dir (e.g. if there's no keyfile then export won't work, if there's no existing keyfile there's no point in doing a backup of nothing when importing). This will be detected on the app start and after each import or export operation and direcotry change, but if the user changes the files in the xonotic dir (e.g. removes the key by himself) while the app is running, then he can use this to recheck and enable/disable app functions. Though if this is really such a problem then I'll rethink this.

I'm also wondering, what does 'remove public key' do?

There are 2 keys in the userdir - the public and the private one. You only need the private one, cause the public is regenerated from it if needed. Now I don't know how the game will behave when you import a new private key, but a different public key is already in place. Hence this checkbox. It's intended for some time later, then I'll check if this is really needed (or if somebody knows, then let me know)