I draw everything in non-render modes (wireframe, shaded, xray, ghosted), I no longer draw anything in render modes (Rendered, Raytraced, Arctic). If I start drawing some stuff in rendered modes then they’ll show up in Rendered and Arctic, but not in Raytraced and Rhino Render and VRay and Maxwell, and and and. This lack of consistency is why we changed the behaviour in the first place. So ideally any solution needs to remain consistent.
Because almost every render-engine out there assumes that is the case. Many of them can’t even deal with quads, we have to convert all meshes to triangles only. Curve piping is one way to use curves in render engines, but it’s relatively expensive and only supports world-units. If a render engine is based in any way on raycasting, then a lot of extra work needs to be done before it will be able to ‘see’ curves and points, because any random ray will almost certainly miss a one-dimensional object.
We may be. We should wait for @andy to chime in, since he knows far more about Rhino as a render platform than me.