It's complex because it involves so many things; people, roles, processes, communication, interactions, negotiations, processes, shared understanding, operating principles, technology and workplaces. Plus a whole range of other things. Improving collaboration requires some knowledge about all of the above, and it is a process in its own right.
The problem with this complexity is that there are as many ways of approaching collaboration as there are things to think about. How to navigate all of this? I've been struggling with this myself for more than ten years. It's really hard!
In about two weeks a decision support tool is being introduced that allows you to navigate this stuff in a meaningful matter; KC Collaboration AnalyticsTM. It doesn't make collaboration simple, but it makes it a whole lot simpler.