kk650 said:

I personally have no problem with Vader being used as a motivating force for any of the characters, so long as they don't resurrect him or converse with him as a force ghost, his character arc is finished and his character/hayden christensen has no place in the new trilogy IMHO

I agree. People can be moved by someone, good or bad, without needing to be related to them. We don't need to see a flashback and we don't don't need to see him speaking to a ghost. Kylo holding a piece of his old armor and having an internal conversation is all we need to see to understand his motivation.

Six films spanning nearly thirty years is more than enough. There are other people in the galaxy.