I might be wrong but why does it allow to import/export a rather lightweight dataset that the regular importer/exporter can't do ?
I will check the placement issue you reported, that shall be "easy" to fix.
Because the import/export only considers the actual geometry and ignores colors and labels and furthermore puts the whole geometry into a single shape.
I understand that independent of the workbench you can always import a step/.../.. file but that should still be possible with a single importer...
The advanced STEP import/export is accessible via the general File -> Open or File Import/Export functions and drag and drop while the simplified version is only accessible in the Part workbench over the Part menu. So, it actually doesn't collide with the general mechanism.
I am a little bit lost on what should be the best option. Roughly to have written most of the new importer, both code rely on the same "process" as they are all relying on Open Cascade. If one of them was using a different backend I could see the interest, but keeping two codes and maintaining them to do the same thing is disturbing. By the way it roughly means that I can make behave the new importer the exact same way than the older.
The effort of maintaining the simplified version is basically zero -- unless the API of the OCC changes but the function itself doesn't need to be changed.
What could be perhaps good if we keep both of them which is fine with me as this seems to be the majority option, I think we shall try to get there code into the same module, took me some time to understand how STEP import was implemented because there is code in Import and Part which are doing the same thing. We shall either merge Import into Part or get the code from Part out of Part and move it into Import. This could at least simplify the maintenance for our next generation developers.
The advanced STEP import is based on OCC's OCAF framework which depends on a lot of other libraries and even includes X stuff on Linux. That's why its code has been moved to the Import
module to avoid that Part
depends on all these additional libraries and thus makes its usage on e.g. pure servers more complicated.