BTB in reach was awful, but I attribute more of that to really awful game physics and even worse, poor map design. But this is how I see Reach vehicles: People want to get stupid easy kills, so vehicles are turned into killing machines. People don't like dying so vehicles are made to be easily destroyed. This results in the worst combination of vehicle balance. Too strong and too weak at the same time. And then throw in a banshee that's impossible to kill as a cool bonus.
I just worry about vehicle combat being the emphasis of any FPS. It dominated in Halo3 BTB, which was one of many things I disliked. Halo2 made vehicles fun and useful, but not overpowered. Halo3 was when you started seeing ridiculous kill streaks by people on choppers and warthog guns. Instead of tight gun play and epic shootouts between people, BTB games were all about jumping into a vehicle for the lulz. Having fun is a good thing, but not when it comletely destroys the competitive aspect of the game. I hope we never go back to that model of play for Halo. If the spartan laser is coming back, then I can't help but think that means vehicles are returning to their d-bag status from 3. Best solution?