I don't really like when people impute motives on others they don't know or understand. Or when they are so close-minded that they try to pre-empt anyone from actually explaining their motivations.
This has nothing to do with being afraid of change.
It has to everything to do with our understanding of Luke's character after watching 3 films and dealing with their legacy for 30 years. We had a pretty solid conception of his character (supplemented by the now-dead EU) that now has to be completely re-evaluated.
If it's a "bold" choice, then it's bold because it seems totally out-of-character. Now, of course and as always, the execution matters quite a bit, but the fact of the matter is that this seems to really undermine what was a solid arc for his character in OT and misses what was a pretty obvious in-character arc in the sequel trilogy (him being an Obi-Wan figure).
And, to be honest, I'm not sure how bold this is, when we've already explored the betrayal of a Skywalker turning evil in the previous trilogy.