I respect your opinion. Though I suppose that's the horror of Kylo Ren - he became who he is despite the family he had (unlike Vader).
I will disagree about TFA relying on the returning cast; actually, I think all the new actors were better than the original actors (especially Adam Driver).
I think what can be taken from TFA is the power of the contrast; the ending of Return of the Jedi completely contradicts TFA, which is the point (subversion).
I personally think the scenes between Rey and Kylo Ren are powerful; when Ren carries Rey off of Takodana, Han Solo watching, the power for me is the idea of Kylo Ren acting ahead of his age - I could be wrong to have that perception.
Overall, the great thing about Kylo Ren is that he is actually the true Darth Vader: Darth Vader wasn't introduced as a tragic character, but became one in time, whereas with Kylo Ren the same movie revealed his true identity, and because his family had long since been introduced to the audience, it made the knowledge of his betrayal all the more horrific.
Essentially, Kylo Ren could perhaps be interpreted as the true idea of a Darth Vader.