I'm guessing cost is part of it. But that tractor has enough tire on it.  Remember an IH 806 normally came with 34" rubber. 

Yes a taller tire might be  a little more efficient as is creates a longer ramp, so to speak, for the tire to crawl out of. But the footprint of the tire, will be about the same whether tall and skinny, or short and wide. 

The 16.9x28 on the Allis 170 i ran, it did just fine for the haying and cultivating chores for which it was intended.