I recommend not going over 4 in your supply since you can only get a max of 4 from a supply station. Get more damage or something instead of that one extra.
But if stations had infinite grenades you could just sit on one and spam grenades infinitely. Cell powers hit harder and have no cooldown. That's why you're limited in the amount you can carry at once.
Also, in campaign it's kind of irrelevant because your carry weight gets ridiculous but in mp if you build your character around cell powers you can ignore carry weight, a huge advantage over many other classes.
