Currently in SP, the only way to make ball joint type rotators is to use 3 individual rotators. This is incredibly frustrating for multiple reasons. Using multiple rotators right next to each other often makes weird rotational inertia issues, it's heavy, and it makes the connections really wobbly when you scale down the mass of the rotators, especially on low physics levels.

Adding ball joints will make building complex suspensions systems so much easier, and would be incredibly useful for several functions, aesthetically and functionally.