Currently it is very difficult to control the angle of 3D elements with relation to a specific plane, and the 3D Angle constraint in particular lacks the ability to be able to adjust the angle between elements in the way that we want to it to. I think a much better approach would be to include planes and coordinate systems as a constraint method to host our graphical elements onto, rather than the current workflow of having to create a bunch of graphical construction elements in order to try and get the granular level of control required for the final elements orientation. This would enable far greater control of complex 3d elements, since we could then specify a value specific to each plane (if required); somewhat similar to the constructs of Generative Components where elements are created / hosted to these additional "construction" planes and coordinate systems, with the option to offset or rotate them in relation to the individual planes available in the model.
Microstation needs a way to
Create named fixed planes AND axes relative to UCS of a file
Create projections of planes onto another based on intercepts, or based on 90 degree projections for an axis projection
Allow lines or features to be constrained to these fixed coordinates, and provide ways for users to trace what is preventing something from being moved or modified if there are conflicting constraints
Right now, the constraint based modeler simply does not help the designer at coming up with better designs. It really needs to do that to help Micro to become more useful to designers and to take more market share from Adsk.
I am not familiar with MSTN too much but i can not see anything like construction planes in Revit which can be useful. Another constraints which would be nice would be "vertical" "horizontal" constraint which would make things much easier. I cant think of o way how to create parametric bridge which is derived from inclined railway axis but bridge itself should be horizontal.....