In a rural setting, I think volunteer units can be beneficial due to the low number of ALS trucks on a given shift. The BLS unit can handle the bs calls that would normally tie up the ALS trucks so they can respond to the calls that need the ALS side.
With that said, I must admit that the rescue squad I run with has gotten away from what the original intent was, rescue. I am certed as a rescue tech (RT) with specialties in swift/surface water, low angle rope, confined space, and SAR. The problem is, due to the squad going more towards the medical side, I rarely get to use what I have been trained for. I feel if the rescue squads, at least the one I run with, would get back to more rescue, the overall reception of volunteers would be better. Of course the downfall to that would be fire depts would see volunteers as competition.