Wouldn't the changes to dimension lines (elevation) also not make it easy to create 3 dimensional poylines (i.e. adding elevation to each of the polyline points). Guess that would also make the 3D-wiring plugin much simpler and beter integrated with the core SH3D.

If I need an 'elevated poly line' I use a very thin and narrow but very wide box [:))]
That 'poly line' I can elevate, change it's dimensions and position easily, and align with other 'box poly lines' and of course other furniture. Something you can't do with real poly lines. Of course useless for the wiring plug-in but the added ways for manipulation are very useful.