[special-K]

The purpose of lock-out hubs is to allow the front wheels to "free wheel",the same as a 2wd. They are an after thought that was not originally part of the design. The axle does not BECOME "live" until the transfer case is engaged from inside the cab. With hubs locked-in and transfer case in 2Hi,the wheels are turning the axle shafts and the driveshaft can also turn. With hubs locked-in and transfer case in 4Hi (or 4Lo),the wheels are turned by the axle. The point of lock-out hubs is to save wear & tear on the front drive parts,tires (some),and fuel economy (less drag).
You can run traction devices in front axles. You would only want a locker if the vehicle was strickly used on poor traction because the differentiation between wheels when turning,as you mentioned,is a concern. A posi/limited slop is what you need in front. GM offered a front posi,that few trucks were spec'd with