I have it on good authority that Graphisoft have licensed the full LightWorks package. And a fine application it is, too!
http://www.lightworkdesign.com/products/overview.htm
Without cynical thinking interfering in an otherwise PolyAnna-ish world view, one might suspect that their motive was to merely SAY in marketing that Archicad has Lightworks and not invest the implementation time to make it any good.
For instance, you are all familiar with Archicad's sketch render engine. Slow, unpredictable and no preview. ICK! See what the LightWorks sketch engine does:
http://www.lightworkdesign.com/products/sketch.htm
It is hard not to be cynical.
On the other hand, i suspect the culprit here is that Archicad might have an obsolete lighting model and that to completely implement these features would require a complete revamping of light and surfaces, possibly requiring a vast expansion of the GDL language. This might make old files inaccessible. Don't know.
Rendering has never been a Graphisoft priority since so few users render within Archicad. Heartbreaking, especially if you are the guy who wrote the book. Several years ago, while writing my first book for Graphisoft, I complained to them about the poor material texture quality found in the library. The officer, whose name i won't say, replied "Let them buy the Artlantis shaders…" He was obviously a descendent of Marie Antoinette whose famous phrase "Let them eat cake [except she didn't mean "cake"]" had dire consequences.
Dwight Atkinson