I've always felt that almost everything NI has put on the market was built upon the technology available in Generator and Reaktor. Whether it's FM7 or B4 or Pro 52 - the components for that stuff were pretty much all available in Reaktor. NI simply repackaged that technology, gave it an appropriate GUI and the rest is history.
Heck, back in the day, the best amp sim I had was in Generator. Granted, it looked a bit weird. :P