The same reason the Fiesta got the Fusion, Corsa, Meriva/Agila, the Polo in a way the A2. Midsize family cars were doing it at the time - think Focus C Max, Megane Scenic, the Touran (kinda), so manufacturers saw some success with those, and repeated it on a smaller scale. If you wanted a small car, but with a taller boot and to look a bit bigger/grown up, they did just that. They weren't very good, and cost more for not a lot more car, but the Note sold pretty well, as well as the Fusion