Why does R2 have the map? Why does Lor San Tekka have a fragment? Legitimate questions. Will they be answered? Who knows.
Why doesn’t the Resistance have the same map? Don’t give a shit.
I agree, if we’re supposed to understand that the map is previously uncharted space. It’s just that I’m not sure what the movie is trying to convey. It was my understanding at first that the map was created by people working for the resistance, searching for Luke. But then I remembered that R2’s had the map since before he went offline, so that can’t be it.
My main point, is that if, by episode 9, it is never explained where R2’s portion of the map came from, I think that’s an issue. I think it’s equally as important as learning where Lor San Tekka’s portion came from, or learning where Rey came from. In other words, I’m fine with it, as long as it’s presently meant to be mysterious.
But if we’re just supposed to understand that R2 has the map because he had access to imperial records from the Death Star or something, I don’t see why the Resistance wouldn’t have the same records after 30 years of access to abandoned Imperial bases and ships.