CCP cannot control the exchange rates, just like CCP cannot control the exchange rate of tritanium to isk.
Actually adding currencies would give more freedom. I don't see where is the freedom in being forced to use a currency that anyone can print.

Who determines that 1 caldari credit is worth 6 isk?

Yet those reasons are nowhere to be heard.

The userbase has determined that 1 tritanium is worth 6 isk, thus 1 caldari credit will be worth 6 isk. If the userbase determines that tritanium is worth 7 isk, then 1 caldari credit will be worth 7 isk.

You say that you don't want CCP to set exchange rates, then complain when players manipulate the market and set their own exchange rates? The irony is strong.

Good luck manipulating tritanium.

The exchange rate of tritanium to caldari credit can be determined by the userbase through a voting system. But once set, it's forever.

It has already happened. For me ISK has no value. I keep all my wealth in tritanium and try to keep my ISK to a minimum. Right now I have 50 million ISK in the wallet. If I need to buy something, I sell some tritanium for ISK and then buy the thing that I want immediately.
ISK will lose its value very fast once people realize that it has no value. What is keeping it from dying is the belief of miners that ISK has value. Once miners stop accepting ISK, it's game over.

Faction currency, because the value of ISK is zero.

In GTNGÇÖs defense, resource backed currencies are much harder to manipulate. However, GreshamGÇÖs law indicates that people would prefer to hoard such currencies than use them as a medium of exchange precisely because they can be an effective hedge against inflation.

Actually that is exactly why tritanium would be a good choice.

During WWI countries went off the gold standard. Then afterwards their monetary and fiscal situations were often chaotic and a mess. So people reasoned, GÇ£WeGÇÖll go on the Gold standard and that will sort it out.GÇ¥ But once you go on something you can always go off. This created speculative pressure for when nations would go off the gold standard and the demand for gold rose dramatically as a safe harborGǪthus the price of gold went up. But as the price of gold went up then the currency price of goods and services had to go downGÇöi.e. deflation. Now using the equation of exchange again,

MV = PQ

If P goes down, then either T has to go up or M and/or V has to go down to maintain equality. The most likely thing to happen is for V to go down. Why? Well the longer you hold money the more you can buy with it in this case. Hold on to that cash long enough and soon it will have an effect on the real side of the economyGÇöi.e people are holding their cash and not spending it on goods and services. So then monetary phenomenon start to have real effects and the solution is obvious. Ditch the gold standard and start printing money (increase M). Countries that did this earlier did much better than countries that hung on to the gold standard.

Now, in the game, the ability of people to mass produce tritanium means that the price is relatively stable with a given set of mechanics. We wonGÇÖt see a sustained price increase for tritanium like with gold above. Trying to corner the trit market would be very hard and prohibitively expensiveGǪand would likely fail anyways and could wipe out the person(s) that tried it.

Still, I donGÇÖt see any of the real world problems with inflation in the game (aside from maybe PLEX prices) to indicate we need to switch to a resource backed currency.

I'd argue that CCP is our central banker. They could, do things like add/increase ISK sinks, they could also change rat bounties. My guess is since they don't see much inflation in terms of game items they haven't seen much need to mess with stuff.

As for fiat vs. gold backed currencies it is much easier to inflate the currency in the former case. During the Great Depression the U.S. government actually shrank the money supply! In 1930s the Fed was out there selling treasuries--i.e. taking money in exchange for government debt. By today's standards it was nuts.

But all that aside I see literally no reason to do this. That one guy wants to consider ISK of no value in game and convert it all to tritanium...fine, whatever. I don't care. Everyone else appears to have sufficient faith that CCP is not going to go off the rails and increase rat bounties by 1, 2 or 3 orders of magnitude.