To me that's good, but thin.
Luke did what he did in ESB and ROTJ out if imminent fear. In ESB, going to Bespin was the only 'vision' related thing he did. Ever. Prior to TLJ. And did he do anything 'dark side' there? No. He was lured into a trap, defended himself and flat out rejected the dark side by opting to fall do his death - which wound up not happening.
Entering the cave, with experience, you would know you don't need the weapons - he was a neophyte and was in a strange wilderness - who knows what's in there. Taking your weapons isn't a wrong move per se. Vader then walks up to him with a saber - not sure who'd just stand there.
In Jedi, as I said, i don't consider it very dark side-ish to want to take out the guy you just watched blow up a couple capital ships and tells you this was a trap and i'm going to kill them all. Then vader tells you i'm going to go after your sister next, again, not very dark side-ish IMO. He stopped when he realized it switch to rage.
Both are FAR FAR AWAY from having a vision in your hut, getting up, walking across campus or whatever, sneaking into your nephews hut and intending to stab him in the back while he's sleeping. There's not much of a comparison. The throne in jedi, pure adrenaline/emotion. Anakin and the sand people, same thing. Anakin/Dooku, same thing. Even luke in the cave was immediate fear based adrenaline. TLJ basically showed a cold calculated decision withdrawn at the last second, but not close enough as it pushed him totally over to the dark side for good. And to cap it off, he shirks the responsibility and goes to hide on a seemingly largely abandoned planet? Just poorly conceived and executed all the way around.
If you want to go that route, you've got to give something more than 'a vision'. Especially when we know visions are not set in stone.
A better execution of that would have been an E7 that picked up at the academy. We see Ben flirting with disaster. We see luke having visions. We see the visions starting to come true (smaller, not very evil ones), We see luke discussing it with han/leia. We get the final horrific vision, luke feels he has no choice, so he goes to the hut finds him asleep and the same scene occurs from there.
If you want to trash luke, you've got to make the investment, not try and get people to buy it off 2 lines or so of dialog. Obviously he did it because he felt he had no choice, but they offered NOTHING to make us believe it which is why it fails. It shouldn't matter a bit that people have built luke up over 30 years of nothing. Actually, it should, because everyone at LFL and involved with the production knows that to be the case. If you want people to buy that as the reason, you have to give them a reason to buy it. 'Just because' is not good enough.
Going back to how you cite the OT examples, you know enough about Luke to understand everything he does. I'd venture no one here would have done anything different in any of the scenario's he faced. I mean, people want to dissect the snot out of the throne room scene (not that there's anything wrong with that) and point out dark side leanings here or there. Here's his literal scenario:
-Captured by Vader
-Brought to the throne room to face the emperor and vader.
-Forced to watch as everyone he now knows is being killed out the window
-The only way he walks out of that room is with a dead emperor, and likely dead or flipped vader
-The other way he leaves that room is dead, or as the emperor or vaders henchman.
There is no 'peaceful' out of that situation. The jedi had no problem killing Geonosians in AOTC. Why should look have any compulsions about taking out either of those two? It's a false equivalency saying that trying to kill either of those two is reason enough for him to sneak up on his nephew to stab him in the back.
