True, agile is a collection of "very small nuggets of common sense wisdom". But one thing that often gets missed is that common sense is often very hard to implement properly; this is where a good agile trainer will help.

I can think of dozens of changes I should make to my every day life based on common sense (don't get stressed, spend more time with firends and familly, save for the future etc). Why don't I do them? Because it's difficult to align these "simlple" truths with the overall complexity of my environment and competing pressures. There's always complexity in the system, agile just simplifies one part and moves complexity into other areas e.g. having a highly trained and skilled team.