If it is a tractor, then it should have steering brakes. Many times you need them to keep your tractor moving in a straight line when using the FEL to grade and the wheels off the ground or not enough pressure to hold a straight line or when you need to boost it around tighter than the wheels will turn to avoid a tree. Get your tractor on a muddy slope wheels sliding sideways and heading for the creek or pond without steering brakes to push you around and then tell me they arent needed.
Heck even my JD 332 lawn tractor has steering brakes. It isnt that difficult to put an extra pedal on a tractor when you have brakes on both wheels anyway.
Very important is that you turn your wheels in the direction of turn and then use the brake to assist. It would put a lot of unwanted pressure on the tires, rim, bearing and of course steering components if you try to just slide the front wheels when facing directly forward.