It's a good point but I think that this speaks to poor editing more than anything else. The fact that many of the general audience seem to have this misconception suggests that the narrative of TFA wasn't clear enough.
I can't disagree with that. TFA left more questions than answers. I'm not going to debate the merits of the "mystery boxes" approach (again: for the most part, I really enjoyed TFA), but it runs the risk of leaving things unclear in a way that compromises the story integrity.
My point is that for this theory to work, someone must have known that Luke was going to the ancient Jedi temple otherwise how did they know to look for a map to that place... But (thanks to TLJ) we now know that Luke wanted to go to the most unfindable place in the galaxy to effectively take himself off the chess board. So if that was his intention, why did he bother to tell / hint to anyone that he was going to an ancient Jedi temple, the two ideas just do not reconcile with each other to my mind.
Luke never had to tell anyone where he was specifically going. Han's vague description about "those who knew him best" thinking that he'd gone in search of the ancient Jedi Temple at least makes it clear that the source of Luke's likely whereabouts was only a select few people (maybe even just one person). Han may have even been talking about Leia. After all, he wouldn't need to mention Leia by name to Rey and Finn . . . they don't know her. Or, Luke could have confided in another person(s) closest to him (maybe a lover; maybe a family friend).
Either way, Luke would be a good enough person to let those who care most about him know that he was leaving, but without letting anyone know specifically where to. And as long as someone knew how hard Luke took his failure with Ben, and knew that Luke blamed the Jedi as much as he blamed himself, there are tons of ways they could've put the clues together as to where he'd be going.
Even if he mentioned an ancient Temple, finding it could be nearly impossible for those who didn't have knowledge about the origins of the Jedi. So Leia eventually starts her search for any clue as to how to find it (like with a map), and comes across Lor San Tekka (who worships and studies the Jedi). That's how we find the situation at the beginning of TFA.
The impression that TFA gave me with was that Luke left after Ben's turn to search for an ancient Jedi temple for reasons unknown. Hence both the goodies and the baddies knew that not only was it possible to find him again but it seemed logical that both sides would actively be working to obtain a map to the place that they knew he had gone to. JJ significantly had Luke wearing his white Jedi master robes in the final scene of TFA and originally had intended for him to be levitating boulders when Rey found him (so not cut off from the force or hiding because he had given up and wanted the Jedi to end).
Which Rian Johnson realized would be a problem because Luke would be on that island playing with rocks after he would've sensed the lives on FIVE planets ending suddenly. He also would've sensed Leia's yearning to bring him back. And Han's death. And he would've responded by . . . levitating boulders on the edge of a cliff? I know that I keep repeating myself, but that would be a pretty big problem if Luke hadn't been cut off from the Force. So Johnson asked JJ to cut the boulder-lifting gag in order to reconcile Luke's continued exile and non-action.
TLJ made it clear that Luke had actually cut himself off from the force because he thought that the Jedi (meaning himself in the context of the current struggle for Ben Solo) did more harm than good. Luke was hiding away and was waiting to die a recluse and a hermit, hoping to take the Jedi order with him (being the last Jedi and all). Luke also changed his clothes to emphasise how super serious he was about being depressed now (unlike moments before in TFA when he was dressed the part of confident and enlightened Jedi master).
There was more to it than just dying and changing clothes so as not to be in Jedi wardrobe. We can make a reasonable extrapolation that when Rey found Luke, and he was wearing the ceremonial Jedi outfit, he was thinking of doing what he tried to do at the end of TLJ when he wore that same outfit again: burn the Temple and the sacred texts.
Luke going into hiding to die alone as penance for his failure with Ben is all fine and good but why go to the Jedi temple at all ...
The Jedi Temple is where the sacred Jedi texts were. If Luke wanted to end the Jedi Order for good, he'd want to erase any wisdom or instructions that could be used by someone in the future to just restart everything. As I mentioned, TLJ seems to hint that Luke puts on the ceremonial Jedi outfit in order to perform that last act of burning the Temple (and scriptures). Even at the end, though, he could never fully bring himself to go through with it. He was conflicted (apparently a permanent trait of the Skywalkers). Along came Yoda.
I guarantee most of your post about this this will be ignored because they like his retcon
How's that guarantee working out for you? Is there anything about his post that you think I missed? Just let me know.