AHH I had a whole response typed up and the forum ate it. I copied and pasted it back and now it won’t let me because it’s “too similar” to what I just posted. I hope complaining here for a second will get me past the stupid forum filter. Sorry!
I agree his character arc is weaker for not having more shown to us of the events in question. I don’t have time to obsessively rewatch movies like I did as a kid so I’m going off my tattered memory. It’s not really clear what Ben was doing that made Luke suspicious.
Maybe he felt Snoke’s influence, or maybe Ben was already planning something with his Knights of Ren (which I have to ask, who tf are they? Another stupid JJ mystery box that had no answer like Snoke and Rey’s heritage?). TFA was not very clear about what naughtiness Ben Solo was up to exactly, and I don’t recall either Luke or Ben explaining it to Rey in TLJ. Which is not surprising, Luke didn’t want to talk to her and Ben is trying to present himself as reasonable and totally justified.
I’m happy to quibble about the execution but I did like the overall artistic choice they (Rian?) made with Luke. But I also like a little bit darker takes on Star Wars, like this and KOTOR2. I’m happy we got a Luke who can’t live up to his heroic reputation and fled, and I think it makes an interesting parallel with Yoda who is another failed Jedi Master (sorry lil green man, I still love you) who retired in disgrace. I like that they are just fallible people whose mistakes can be orders of magnitude worse than your average person’s because of super powers.
It’s possible that I and the general fan base diverge on the subject, and I suspect another director isn’t likely to be allowed to make story choices like that in a flagship property. We might have our Rogue One side properties where there is a tragic story arc, but after the fan backlash I think Star Wars will probably stick to safe heroic fantasy going forward.