Currently R-click intuitively changes the armor to exactly one armor type as it should (the last selected one).
1/ If it should change the armor to something else, how would it know to which one and when? Let's say you have 10 variants of the same armor (grey, red, blue, green, yellow, black, white, etc.)... how should it know which variant to pick?
2/ And more importantly, why should it even try to do something else? The player expects and wants to change the armor to the one he selected, not to some other random armor. If the player wants to use a different armor, he uses L-click, instead of letting the game blindly guess what he might or might not want to do.
If I misunderstand something, give me a concrete example, in excruciating detail, step by step, without omitting anything.