Well, at the time the quicktime decision was taken there were still MANY codecs that needed to be supported and QT was probably the easiest way for developers to make sure everyone is sticking to the SAME version of that codec.
I remember how the installation of a DVD burning program (NERO) messed up my Windows XP installation so badly, that I could not get motion jpeg files to play on my machine anymore in full screen.
Microsoft had their owen (very messed up) way of deciding wich system component to use when showing a video file. Quicktime offered the opportunity to have cross plattform support with different codecs in a simple “if it plays in Quicktime on your machine” it will probably play on most machines" kind of way (while keeping the need to buy licenses for different codecs low for users and Steinberg)
As technology moves forward things change, and we’ve all had our share of “video engine is not working” bugs in the meantime, but generally speaking I would say it’s now rather solid in Nuendo and once you’ve got things working, you can almost not mess it up later (at least I’ve never managed to do that).
We’ve also got TC burn in and ADR, so I’m happy. You only need to set this up once…