I believe adding buildable bank spaces to the game was a mistake.
If we can build a bank on a remote island, why not on our boat, in our POH, or in other remote locations of the game.
Also, this could have been a very nice expansion on lore/questing. Revealing the CBG (Central Bank of Gielinor), who is behind the banking system.
Locations/NPCs that offer banking systems can then be tied into this in-game entity, with them deciding where to add bank access in the world.
Some banking spots can then also be rewarded from quests or mini quests.
Not having a banking spot nearby just feels like an arbitrary dev decision now, while it could have been a nice story line within the existing game world.