I haven't been able to take other soldiers or civilian fatigues. I want to be able to because I need to take the supplies with me. It be better to take them instead of having to put them in mine.
Yes, it is against the Geneva convention but no country is going to follow the Geneva Convention and no soldier is going to put his life danger over a stupid treaty.
The actual reason is that BI doesn't know how to handle changing fatigues and AI.
When should the AI realise that you are an enemy? When should they engage? Should they engage at all? It could be a game breaking feature, and I can't see an easy solution.
Maybe they could do it with the current friendly fire system? But with a really short fuse? But that would also mean friendly forces would consider you hostile, of course. But the problem would be with switching teams...