The travelogue of what missing characters have been doing while they've been away is important to fill in potentially important details. Just think about all the stuff Gandalf got up to when he was off on quests of his own away from the hobbits.
Or you can leave some of the details unstated to create a bit of mystery.
Commentary by memnarch (who has not seen the movie)
Wait, Luke passed on the location to Lor San? I'd thought that they'd found Ahch-To together. That would mean Luke hasn't passed the info on to anyone yet; it'd be all on Lor! I guess this could be the usual drift of player memory, but as it's a comic idea, I don't expect the curse to have a future effect either way.
Huh. Luke does have less grey hair here than when he was on Achoo. That is rather funny. Also amusing to think it's a Force power that he used to make himself look old, rather than trying to look younger here. It's probably just meant as a sign that Luke is feeling more engaged with events now rather than a mentor thing, but I doubt there was much more thought put into it than that for the movie artists.
Transcript
Leia: Where have you been?
Luke: I found the lost world of Ahch-To. I sent Lor San Tekka to tell you. Didn’t he?
Leia: I sent Poe to find him.
Luke: Ah, enough said.
C-3PO: But if you gave Lor the location of Ahch-To, you’d have been doomed!
Luke: Maybe that’s why I crashed my X-wing into the ocean.
Leia: So how did you get here?
Luke: Rey found me. Said you were holed up here on Crait.
Luke: I used the Force to make myself look older. To play up the wise mentor schtick.
Luke: She gave me back my underwater oxygen extraction apparatus. After she left I dived down and got my X-wing working.
Leia: And what did you tell her?
Luke: The truth. About me and Mara Jade. And her.
Leia: So she knows I’m not her mother.
Luke: On the bright side, Han’s not her father.
Kaydel Ko Connix: {sotto voce} This family is nuts. Maybe I’m glad I’m not part of it.