I've searched everywhere for an answer to this, but I can't find anything that gives an indication of why some of my maps have "value" and others don't.
What is meant by "map value" and how is it calculated?
In the Leaderboard page, there's information about how it's calculated in the "?" tooltip at the right next to "Go to cumulative LB":
... says:
How does the Point System work? The maximum points tally to be gained per map is defined by the map value. Points within the map are distributed based on the best replay times as score (e.g. P1 - 100%, P2 - 80%,...). The map value increases as follows:
+1 for every new player
+1 for each beaten replay (+2 for featured maps)
+1 for each position improvement (hunting bonus)