Vectorworks Architect is (unfortunately) not a BIM competitor to ArchiCAD (or Revit, etc.). You'll be told it's a "BIM tool" but that's just a euphemism for admitting it doesn't compete with the likes of ArchiCAD.
ArchiCAD, first and foremost, is a dedicated building modeller so it needs to ship with a building modelling environment that allows one to model buildings. Vectorworks, on the other hand, while a very capable general modeller and presentation tool (catering to a number of industries) is hardly worth mentioning on the building modelling front.
This freeform modelling capability, on one hand a major advantage, is also an important reason why Vectorworks Architect is lagging it seems to me. It doesn't *need* to ship with a workable building modelling environment in order to model buildings; one can simply resort to freeform modelling. The problem, of course, is that modelling buildings in freeform is generally uneconomical (especially for businesses of more than one person) so you end up stuck in a 2D workflow, or semi-3D at best.
Another reason is that NNA appear to have dropped the ball in a major way with regard to their BIM strategy. As you'll see by this rather lovely thread NNA's main BIM strategist thinks "The primary component of BIM is interoperability…" (note that he's an engineer, not marketing!):
http://techboard.vectorworks.net/ubbthr ... ber=127462
It's mind-boggling that they actually believe the ability to share information is a more important than producing it. You can't just take a 3D CAD app, slap on IFC compatibility and call it a BIM competitor to ArchiCAD. I have a pretty good appreciation of the importance of IFC, interoperability and the ability to work in teams work but there's absolutely no point in any of it if the designer can't produce the information in the first place. Interoperability and building modelling have to be equal partners.
It could take them another 5 years to catch up, and then only if they realise they've dropped the ball.