I hate to suggest other software here, but as long as you promise ONLY to use it for file conversion...
I've recently read that (the free) Autodesk123 can import STEP and export 3d DWG....If true, that might be worth a try. I made a brief attempt to find a feature list for the products but all I could find was a download screen and I was not committed enough to go through that.
On a broader view of this topic, STEP files have become the most generic format in industry by which manufacturers distribute 3D models of their product. If you do 3D mechanical design, it will be a great handicap NOT to be able to be able to bring in 3d Models from component suppliers. (Unless most of your product is internnaly generated & stays in-house).
It was this need that drove me to add a solid modeler to my CAD arsenal.
I dont expect to see much development work in this area either. There just isnt much demand for it.
a demand for 3d DWG/DXF to
STEP translations, as mfrs have legacy models that would otherwise be wasted....just not the other way round.
This is unfortunate, there are still things I can do with DCAD that I struggle to accomplish with other tools.