The ability to turn all diesel locomotives in a consist at once from one loco. Would make multi-headed and push-pull consists easier to manage.

Generally speaking, this is not something MU-capable diesel locomotives are able to do. Earlier generations of diesel locomotives in particular require each locomotive in a consist to be started manually from within the engine compartment.

Yeah, I think it's enough that the throttles and brakes be synchronized, and properly reversed for locomotives connected in opposite directions (which I think will be new in the next version).

They already reverse based on loco direction.