I did agree for Mysterious maps would be nice to stack, but for me minor convenience I don't mind as it is.
maps from questing :
Day 1 : just had time do quest got map and deciphered it
Day 2 : same, got map undeciphered in inventory
Day 3 : Did 2 maps, the quest and then the 3rd map.
I am not saying they don't have to change, I guess there are people that don't have a problem with it either way.
Maps bought with myths you can only buy 2 before having to farm Myth again. There are a some people that do farm alot.
If you can stack you go to Mordhona and then Myth farm, Spend myth rinse and repeat. Then once enough maps you go farm all your alexandrites you need.
By being so focused you would reduce alot the time to collect your alexandrites.
There will be always time sinks and the relic is one of them.