Krugman is a post-Keynesian which is very far from Keynesianism. Gravity is still a theory. MMT really just states facts about how modern money works now and the artificial legacy restraints in place and offers policy suggestions. I admit Wikipedia may not be the best source due to its editing nature so there are better sources like this free book link “seven deadly innocent frauds” by Warren Mosler who made a lot of money from understanding monetary sovereign countries don’t have to default but can only by choice: http://moslereconomics.com/wp-content/powerpoints/7DIF.pdf
Otherwise this short clip of Greenspan schooling Paul Ryan may tweak your interest. The look on his face at the end is priceless: https://m.youtube.com/watch?v=Ccb_BNdRN80
Modern money explained 3min short version animated: http://youtu.be/bTZGU9s0idM
30 min long version with narration: https://youtu.be/bHQCjFebIf8
Also MMT very much talks about taxes being essential but the form they are in could be greatly improved. Yes there’s government waste but there is an incredible waste in the private sector too. Why use humans to wash cars or flip burgers when it can be automated. Use humans for something more productive and meaningful.
Series on taxes and MMT here: http://neweconomicperspectives.org/2014/05/need-taxes-mmt-perspective.html