@Michael:
What about only position/align parts with face-face way with given offset value:
https://youtu.be/xtZhw4egOGM?t=2512
It`s used in assemblies but I think it would be also nice way of positioning things when you hit two faces and both objects are aligned perpendicularly according both selected faces. It works nicely also on circular faces (f.e. bolts in holes).

I know there are many ways of doing that but having that feature with present offset value could be also useful IMO.

@beanwork:
If you have Rhino then you should consider buying Bongo for IK mechanical animation:
https://www.youtube.com/watch?v=kWtekHNl894
https://www.youtube.com/watch?v=grAN2_BxNFQ
It`s animation not simulation but I think it`s quite similar.

If you don`t have Rhino then maybe FreeCAD will be able to simulate MoI3d models as you want:
https://www.youtube.com/watch?v=D1jigCuD9jM
https://www.youtube.com/watch?v=8-wYmGekF2c
version 0.19 of FreeCAD was released few days ago and it`s quite nice to try (and free).
I`ve tried it lately because I wanted to use it together with MoI3d and Rhino.
I`ve imported some MoI3d parts into FreeCAD as step files and it worked quite well.

Cheers!!!