I wouldn't expect a toro employee to be allowed to point this out, but want the real reason there are no antiscalps? It isn't the wheels fitting, or that they aren't needed. It's that the deck is now too heavy with the engine mounted to the deck. The antiscalps would cause the deck to gouge the turf instead of rolling up over it.
Personally I think the 36" will be fine without them. The 40", due to the decision to narrow the front casters in the interest of "trim edge", will likely scalp leave noticeable uneven spots when mowing at lower heights on undulating terrain. It's simple geometry. How could it not?