Inaccuracy due to lack of level will be small and can be accounted for. What isn't necessarily small and is difficult to account for is varying loads due to local winds.
I wonder if some of those with larger wheels were expected to operate from grass fields where the larger diameter offers lower rolling resistance and lower the bending load on the thinner/smaller nose gear. I note the balloons used on bush planes, for example. The mains, being already beefy would not require a lower rolling resistance.