Space isn't 2d
Travellers mapping was always a kludge for simplicity, even ignoring the z access a system could be over 3 light-years out of position, Traveller had many good things about it (though Megatraveller=worst Traveller if you ask me, no I'm wrong, Mark Millers Traveller (Traveller 4) actually was) but mapping was definitely not one of them.