I saw a very old post about treasure maps and how they become superfluous as you play the game (the resources from them can be earned quicker in other ways).
What I didn’t see was my idea of using treasure maps to craft vault keys! We could come up some scale that makes sense like 500 treasure maps and 1000 souls for each key.
I don’t know about crafting, but I think that there should be a feature to use multiple maps at once for greater rewards. Similar to how you can power up your characters for various events by spending extra sigils on the event battle page.
Another option would be to simply add vault keys as a reward for playing the maps. If it were possible to get them fairly consistently, I would use the maps way more.