So I'm back after a couple of hours of conclave, and for the most part see little problem with it.
It mainly changes the monarchs and other nobility of a feudal state from a totalitarian god-dictator to a human being who happens to be a king. And guess what, other humans have different opinions than you, and in your own realm!
Changing law structure is, I will admit, more tedious now. Especially with tribal governments, as you have to do a TON of law changes to westernize or toss away gavelkind.