Inconvenient mounting. We have already got used to wheel pairs in magnetic construction sets, where the wheels are permanently fixed on a magnetic piece, which is much better for construction. This way mounting wheels is for older children,. Meanwhile, with wheeled rods or bases, even a 2-year-old child can build simple cars or locomotives on their own.
Wheels are also can used as a design element in crafts along with the eyes, headlights, motors, etc. Putting the wheels on the rods/axles may be tough. The wheels are made of silver plastic.
