I don't know why Bungie didn't think of having hotkeys or if they don't know how to implement them? There's nothing worse then being completely immersed in intense combat and to run out of ammo and have to enter the menu, go to inventory and select ammo synthesis from there. It's not that big of an issue but I think it would go a long way to keeping players immersed in game. wouldn't it be cool if you bring up your ghost, hit a button (clicking left analog, maybe?) and your ghost would go to the center of the screen and around it would be your ammo synthesis, your other sub-class (switching from Defender to Striker) and even other weapons (switching Fusion Rifle for Sniper).