> > > > > Folding of proteins and post transcription modifications are significant enough and different that for instance insulin can only be made in eukaryotes if you want it to really function well in human systems.

Well, there are ways around it. Some companies produce insulin in bacteria, while others produce it in yeast. It's a tradeoff since yeast is better at making it correctly in the first place, but is otherwise a less efficient and more complicated expression system than bacteria.