The two lightsabre duels at the end were just stupid. They were there just for the sake of film having a lightsabre duel. And if they really had to make it like this, at least the dark side guy should kick both of their asses. And please spare your time, I really don’t want to hear dumb arguments such as: “but she practised with pole stick” or “he practised with stun baton”.
Ren was a poor villain
I wouldn’t go far but I’m sure the point of the scene is to show that Kylo isn’t as powerful as his walk makes him out to be.
Rey was simply lucky?
Pretty much just like Luke blowing up the Death Star. Both things were pretty much impossible but they both happened because it needed to be established that our main characters are uber special.
That is pretty much the opposite as it should be. Establishing a weak villain is a bullet in a knee for a film. If he kicked their asses and “sent” them back home training, it would at least add some motive to the story/characters.