I'd like to see more variants of Ghosts, Warthogs, the Wraith and Banshee. For example, a Ghost with twin-linked fuel rod cannons, a Warthog without a gun and can hold 3 people in the back, an anti-air Wraith or a Banshee that is made for bombing.
Its not that bad. It's the only good pistol in the game. I believe its balanced because when you charge it, it takes about 2 seconds before you can fire.
It'd be awesome if they came back because they seemed to create a purpose to rush some levels of the previous games. If Halo 5 included the Flood, an infected Spartan would be a deadly opponent.