Should it return? Why or why not?
Yes.
Because it’s awesome and it was the only useful Turret.
Personally I think it’s redundant. There are so many other anti-vehicle weapons that could potentially return.
There really needs to be a maybe or don’t mind category
Yes.
I want the rocket launcher to revert to Halo 3 state, for numerous reasons (one of them is so that gravity doesn’t affect it again; you’d think by 500 years they would have calibrated the fins on a rocket to keep it level).
It’s also nice to have something that locks on instantly. If the rocket launcher did this in Reach, we wouldn’t have as much of a problem with Banshee killing (although you don’t really need it because of the DMR, let’s hope they fix that for Halo 4).
Always nice to be able to lock on to ground vehicles.
But mostly, I want it for custom games 
Tons of fun options with it and rocket launcher both existing.
It would be nice to have it return. It served as a really good anti-vehicle weapon in Halo 3 so I have no problems if it did return.
It was fun to use, so yes.
It doesn’t need to return. The plasma launcher works as an antivehicle weapon and they can just make the rocket launcher’s lock-on function better (it sucks in Reach).