Kylo makes a proposition to let the past die (merge light & dark sides to stop fighting all the time, great) then backtracks & the hunt for rebels is back on. let the past die or not?!
Jesus man do you want movies to be interesting or not? Have you ever said to yourself - 'I'm going to start acting this way' and then went and did the exact opposite thing immediately?
Having characters flip flop around is not interesting. Kylo’s choice wasn’t what cereal to eat in the morning. He murders his master & the top guards (aka treason) then backtracks