Main idea: If gold and/or grog storage units are not full, to be able to move loot from one unit to another. If you have storage units that are more exposed to attackers, by moving loot to more protected ones you could have the exposed unit become a lure for attackers that will give them little gain. It would be sort of like emptying your collectors before going offline.
You can kind of do this already by checking how much loot is in each storage, and then placing those with the lowest amount near the more exposed parts of your base.
Hmm. This is a tough call. I both love and hate this idea. The strategic defender in me loves anything that can be used to misdirect and generally screw with attackers. We could have fun with this. on the other hand... The wall-hungry raider in me hates it. One of the biggest problems in the game is there's not enough loot at most levels, and this would make it even harder to get.
I am against this idea. As @Kelani pointed out, it sounds great as a defensive strategy. But on the other hand if it was available every pirate would consolidate their gold/grog in one storage and make it near impossible to reach. Most of the "fun" in this game comes from attacking and gaining loot. This would takeaway from that aspect. On the other hand, I am in support of a "buried treasure" feature that has been mentioned before. That idea would solve many problems for players high and low that need to save for upgrades without having to restart everytime their base gets ransacked.
On reflection, the buried treasure idea is probably better. My idea is definitely love it/hate it kind of thing!
I'm with @porrig and the others on this one: 1. what ever I have more of (gold/grog), I move those storages to the most secure area of my base. 2: as soon as I have enough to spend, I do (I never let my storages fill). 3: and as the others have pointed out obtaining vital resources is becoming more and more difficult. But, I appreciate and share your concerns on wanting to protect your earnings though.
My strat: Expose 1 Lvl 1 Grog Distillery and 1 Lvl 1 Gold mine. These lure attackers right into a crossfire of mortars, cannons and Gun Towers. So, this idea is literally already present if you think about it.