And Vader never held a blaster bolt in mid air like that. Ren’s potential is actually frightening.
Unlike many who dislike the film, I had no problem with that. I don’t think of Ren as being more powerful because of it, though. Perhaps different Force users tap into the Force in different ways. We never saw Vader zapping people with lightning, or Palpatine/the Emperor choking people. What cheapened him for me was his lack of proficiency with a lightsaber–against people who had never held one before.
You can be great at swinging a baton around, or shooting a gun, but be totally out of your depth with a sword. Finn and Rey had very little to no training with a sabre, while Ren almost certainly had some, yet he and Rey were equally matched, and even Finn held his own for a little while.
The official explanation is Vader can’t do Force lightning with his artificial limbs. The detrimental effects of getting zapped by Palpatine on his life support systems is probably another factor.
Finn probably had some training with the saber resistant staff the “TRAITOR!” yelling trooper pulled on him. He still almost gets killed.
It’s a safe bet Rey had some training when she was very young, but does not consciously remember it, hence her ability to do the mind trick. And we saw toddlers training with sabers in the prequels.