Rhino files import
When importing .3dm files in BricsCAD all the 2d geometry imports as splines. In AutoCAD circle imports as circle, arc as arc, ellipse as ellipse, rectangle and polygon as polylines and freeform curves as splines. The same with 3d solids  in BricsCAD all the edges are recognized as splines, but AutoCAD properly determines that a hole is a circle, not a spline, that a cylinder base is a circle and can be properly dimensioned!
Comments

Have you tried export as a dwg. There are various Schemes that you can select and edit and then save for future exports.
I had to do a similar thing. Works perfectly now.
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In fact, I'm using MOI 3D, not Rhino. I can export as .dxf for 2d and preserve the geometry, and for 3D running "Simplify Geometry" does the trick but my point is not to use any workarounds when the direct import is capable of all this  as does AutoCAD.
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