I don't know why did they try to connect the two so tightly, they share so little in common other than being force users.

Kylo Ren's conflict has to do with Luke and his parents, Rey has to do with Palpatine. So it was completely different. And both of their conflict was missed. Especially Rey with Palpatine, that's one of the weakest part of ST. Even PT did a much better job on Anakin and Palpatine.