As someone who does all six crafting writs on eight characters each day (soon to be twelve after DB), I spend a significant amount of time managing my survey maps. Now that crafting bags are here, I'd say survey maps have become the most painful element of inventory management. When I saw the new change that allows a survey report to pull a map out of either my inventory or my bank, it occurred to me that maybe the same infrastructure could allow survey maps to stack, or at least to no longer be unique. That would make crafting writs significantly more enjoyable for me and likely for others as well, letting me collect the writ rewards for longer, and then go and get a bunch of materials all at once as I have more time.
Treasure maps have the same problem, though less frequently. A typical scenario here would be someone who is buying Wrothgar maps as a way to obtain the BOP sets that are slow to get in other ways. For these scenarios, having treasure maps not be unique would significantly decrease the amount of time just managing inventory, and increase the amount of time finding treasure. This change would also make treasure maps a bit more efficient to use, which would likely increase their value in the game. As I was shopping today, I saw quite a few maps selling for below the amount of gold that you find in the chest, indicating that in most cases, the rewards just aren't worth the time. Making the maps easier to manage would help decrease the cost of using them and maybe make them a bit more rewarding.