So referring to bikes on a sailing forum.
The stiffness was very important in the bb for power transmission and also solving the down hill wobbles a major problem with some designs.
The wheels are moving so the weight savings in wheels are seen as very important- particulary the rim,tyre,tube combination as they are the furthest away from the centre of rotation. less spokes doesn't solve this problem in many cases as the rim has to be built stronger, but they look nice.
Back to boats, in Australia we have carbon rudder boxes mated with foils that are heavier and more expensive than aluminium but they're popular because they have the "porn" factor