Everything is worth what its purchaser will pay for it.
~ Pubilius Syrus, Maxim 847
In theory, the seller sets price(s) which makes him the most profit or value. Perhaps a particular seller values market penetration over pure money, so he is willing to reduce the price so that a greater number of units are sold.
With region based prices, the established price takes into account only the people of that country or region. Region pricing almost certainly advantages the seller and people with less purchasing power, since the seller can make maximum profits where they are possible, and still make some profit in other markets, which might not sell sufficient units for profitability at the same price as another market.
With a currency-translated world price, the established price encompasses everyone with an internet connection. The seller is no longer able to both sell to the smaller market while maximizing his return in the more valuable market - instead, he has to balance his price into a new equilibrium for both markets.
Neither of these two situations quite describe the situation which Elemental and Stardock face however, because they are trying to offer a single price to a world-market while others are offering region controlled prices for the same type of good. It also means that they naturally cannot work within the different price-fixing standards of each particular market. Since they are also offering Elemental at retail, they are stuck with the constraints put upon them by the retail markets they are participating in.
With all that said, I applaud Stardock's position on regional pricing. I look forward to the day when games are purchased for what they're worth (good games being worth more than the kruft that is so often shoveled out there today) - and view world pricing as a step in the right direction away from the commodity based pricing of games [all launching AAA games in the USA are commonly priced at 60USD regardless of quality, I consider this bad].
EDIT: Incidentally, the implication of the quote is that it is best for the Seller if he can charge exactly what someone is willing to pay for every item he sells - be glad you live in a reasonably mass market which prevents that.