The 'fair trades' concept based on the gold/supplies needed is actually resulting in a ridiculous situation where people don't want 4x4 production clogging up their cities when they can't get genuine return for value so they don't have them. 'Fair Trades' thus creates the critical shortages it's supposed to prevent!
I'll be very interested to see any informed and thought out rebuttals of this agrument.
The fundamental problem with this entire thread (and the numerous ones similar to it) is the use of the term "fair trade". All trade is, by definition, "fair" in the sense that its not coerced. If you aren't happy with a deal, you don't have to take it. If you elect to take it, by definition you are happy with it.
What people are describing when the talk about their guild rules is not "fair" trade, but rather "orderly" trade. Most guilds have found that agreeing, in advance, to a set of exchange rates promotes orderly trade among members, because it eliminates the possibility of a "better" deal being out there if someone waits just a bit longer.
Whether that ratio is 2:1 or 3:2 or 6:5 is irrelevant. The key is that its set in advance for all members of the guild.
Yes, you can find arguments for why a particular ratio is more appropriate, more precise, better reflective of true "costs". However, they are all derived in one way, shape or form from a measure of input costs. If you only look at the coins and supplies, you get one calculation. If you attempt to adjust for the difference in the size of the buildings in a particular age, you get a different calculation, etc.
Now to your thesis, which is that fair trades create shortages. While you correctly identify one criticism of some of the more popular goods calculators (i.e., that it simply measures coins and supplies, not building size), you then fall into precisely the same trap, which is to view trade as static.
1. While, all things being equal, I would rather make the same goods in a 3x3 building than a 4x4 building, the game, not me determines whether I have a boost in a particular good.
2. If everyone produces Age Good A, there will be a shortfall of Age Good B. There will be some people in that world with the boost for Age Good B. They will eventually come to realize that it is to their advantage to produce Age Good B and trade it for other goods they need. While they may not be able to trade that good at an advantageous rate to their guild members, due to its internal "fair trade" guidelines, they will be able to trade it outside the guild.
One of the more interesting parts of this game (to me) is that, unlike similar games, it has created a robust market for its goods. You can argue the 2:1 1:2 extreme limits are arbitrary (I agree), but within those confines, meaning trade within 2-3 ages of one another, the market actually functions in an orderly way.