It would have value. That's what I've been trying to say. The value would be that it is easy to use. The value would be the same as the resources and items that it would be used to purchased. If I was designing this system it wouldn't just be for player-to-player trades and taxes, though. I'm almost certain that I've said that in this thread on numerous occasions. Unless money entered into the game at the same rate as new players and new resources entered and items left, then there would be inflation. So having currency sinks would be a design choice that would help limit vast price fluctuations, and depending on how it was implemented could provide additional layers of player choices that can't be had from just an item-to-item tradeing system.
Shrimps, I already addressed your first sentence by using the term "programmed currency." I assumed it was obvious that I meant that the developers would have it programmed so that that was the currency that was recognized by whatever building or object serves to assist players in tradeing with each other. Shrimps I also already mentioned Metro 2033 in this thread as a way I'd have liked to see currency introduced into a game like this. I think it's an honest shame that there won't be guns in this game. The whole being labled post-apocalypse thing threw me off.
But money wouldn't be useless. I don't know how many times I have to reiterate that. Actually, think about it in the real world. Money is useless since you can only use it to acquire things that you really could get by tradeing your things or services to someone else for things and services. But that's not really true is it? No one has the time to actually trade favors to each other for all the things they need, and I really doubt that you would be able to trade some things that you own for something at the grocery store. So what happened? Governments instituted currency systems to help people trade and perform services for each other. The only reason it works is because everyone accepts it. Otherwise it has no value, just like you two have been talking about. Let me say it again, a currencies value is in the fact that everyone accepts it.
As I mentioned in this thread, the developers would have to program the currency to be accepted for trade. That is it's value. The value is that everyone accepts it that uses that system to trade. You don't have to worry about not having the right things, because they could just take your currency and trade that for what they want, much easier than taking your items that they don't need and then trying to find someone else to trade those items for the thing you really want. But, even if a currency system is implemented into this game it would not take away your ability to trade item-for-item.