The WC-51 currently has both a combat role and utility. Take away the WC-51's utility and all that it'll have left going for it is the cheesy and arguably OP garrisoned Cavalry Riflemen combo, which is something I think most people will agree with has to be toned down. But nerf both and the unit will never see use (like the Kubelwagen). So the way I see it, nerfing its combat cheese potential and leaving its utility is the only way to keep it viable.
It's an early bleed tool, a capping car like a Kubel, and fuelless AT if you stick a bazooka squad in it.
Maybe it can have those abilities if you stick a Major in it, but otherwise they're utterly incongruous.