I have a Weaver Little Joe and a pair of MTH Bipolar electrics. All great engines.
Don McCuaig (Scale Rail) is the one that tried to get the manufacturers interested. As far as I know, the only electric switchers in O scale/O gauge are out of production 2-rail brass models. There are plenty of railroads and trolley lines that used them. An MTH 3rail/2 rail convertible model would make sense from a sales/marketing point of view. They may even be able to share parts from the MTH 44 tonner.