There are I think a whole heap of issues with wheel stability at high speed and a ball doesn't actually give you better grip.
And the further out the axle support is the beefer the attachment needs to be. Then if you go for two wheels the control forces get higher and thus things need beefed up.
As with all things its a historical compromise. I have no doudt there have been several iterations of nose gear design which were done years and years ago. And the one we have now turned out to be the best option for light aircraft. Just as the 2 wheeled live axle turned out to be the best for bigger things.