What was Wizoo is what we now know as Digidesign's A.I.R. group (Advanced Instrument Research Group) who are responsible for the recent crop of PT virtual instruments... you could even argue that Strike would have been GrooveAgent3 had Digidesign not bought Wizoo when they did
The only main difference with VST3 on the surface is side-chaining and improved multi-channel operation (all VST3 plug-ins should automatically be multi-channel capable.. e.g. stereo or 5.1 or 7.1 or whatever). It's an evolution of the architecture that was inevitable... it seems the 3rd party developers are just grumbling 'cos it means more of a change for them than if SB simply extended VST2.4... obviously that route wasn't in SB's best interests.