Why is the "force in being" - effect of this card, namely that it discourages players from stocking huge warehouses, necessarily a bad thing? I think trade should be something we should be able to attack.
If the effect of this card is removed, then it will not be possible to target warehouses anymore. I dislike things that cannot be attacked. I think we need a way to be able to attack warehouses, so if this card is removed, we would need a new way to do this.
Another thing that currently cannot be attacked, is plantations. If this card needs to be changed, then I suggest changing it so that it somehow can be used to ruin plantations.
Also, I disagree that the fact that it is now slightly easier than before to locate a target's huge warehouse, that still does not cause a need for this card to change. If anything, this card was underpowered, so making it slightly more powerful is not a bad thing. Personally, I would like to make it MUCH more powerful, by allowing it to target a specific resource. That way, it will be possible to target both large warehouses and plantations at the same time.
Anyway. If it has to change, I'm in favour of something that can be used to attack plantations. Anything that is completely safe from attacks is bad in my book.