By default the numpad numbers control the view directions. Since the mouse also controls the views it seemed a good idea to unassign the keys and use them for other purposes. This works as it should.
The numpad numbers also move the ingame map around which can also be done with the mouse. I haven't found a way to unbind the map controls from the number keys. If I reassign the numpad number keys to something else (in my case to Teamspeak whispers), I cannot use the map at the same time because the map would constantly move around.
This isn't new. It has been carried over from ArmA2 and maybe even ArmA1 and OFP, but I still consider it a mistake because free keys are so rare in ArmA.