What would be really nice is scene graph heiarchy for objects.
In Unity 1 object can only have 1 collision box. So it's not unusual for 1;1 ration. it's nothing new. However many engines I have worked with use SceneGraphs and non scenegraph engines like C2 are fewer out those I used.
A scene graph uses a parent->child relations. This makes the XY, Size, angle all relative values compared to the parent. While PIN does this to a lesser extent. it's a far inferior to scengraph.
In Unity when we need multi sensor objects. We create the core object and then child objects with additional colliders. Because unity uses Scenegraph this is easy. If I flip/rotate(ie Mirror) the object and children are mirrored with the parent. This makes handling multi part objects super smiple.
Now I love C2 more than Unity. Much more, but I do disagree with a few design decisions. PIN is not a replatement to Scenegraph design. And scenegraph design would fix a lot of problems developers have with C2 and object structuring.