Valid points about giving Kylo such an ignoble defeat so early in the trilogy. Although how big an issue it’ll be for the viewer depends on whether you see him primarily as an antagonist and threat. For me, the fact that they let us know so early he was Han & Leia’s son had me seeing him not as a Big Bad for the heroes to ultimately overcome but rather as a quasi-protagonist in his own right, a screwed-up character on a journey of his own (of course, whether that was a good story decision is a different question).