From late WW2 onwards, many aircraft designs started using the
tricycle undercarriage scheme. Prior to this, most used the other one
(you know, two large wheels up in front, with the plane tilted back
onto a small support wheel).

Why the change? Well, good visibility (while taxing/take-off/etc.)
would seem to be a huge advantage of the tricycle undercarraige ... so
I suppose the question really should be - why did most aircraft NOT
use the tricycle undercarriage design until late WW2?