hucklebarry: I stand on both sides of this issue at various times. As for the OP, I don't think your argument is very sound. The cost of EVERYTHING else is going up, the cost of games isn't going down because people don't have money. The price of going to the movies has doubled in my lifetime. The cost of new games has also gone up.
Actually, adjusted for inflation, the price of going to see a movie has remained roughly the same, at least in the US (Germany too, but in the UK it has indeed risen considerably), and the price of games is also cheaper when adjusted for inflation.
Part of the decline in prices is certainly due to the economic problems, but note that this decline started before the depression came. Prices going down is simply a manifestation of market forces at play - the market is aware that there is infinite supply and zero cost of reproduction, so they are applying pressure to adjust the price accordingly. In economic terms, the only value associated with a digital licence is that of 'goodwill'.
It's essentially economies of scale. We pay money for beer because (a) water, hops, barley and yeast all cost money to produce and (b) the amount of beer is finite. If two bottles of beer cost $5 to make in total, then each is worth $2.50. Demand in the face of scarcity combined with market control/market entry barriers raises that price and creates profitability. A brewery can increase its profitability by making more bottles while applying economies of scale. Each bottle it makes will be cheaper, because you only need one machine etc. mass production becomes cheaper, so a brewery can make 100 bottles of beer for $150, charge $2.50 and make a meaty profit.
Now imagine if someone came along and invented a machine that makes bottles of beer perpetually without the need for ingredients. It just keeps pumping out bottles. If one bottle of beer can be made with it, it is worth whatever it cost to make the machine. If two bottles of beer can be made with it, it is worth whatever it cost to make the machine divided by 2 and so on.
The inventor is overjoyed because he can charge $2.50 for endless bottles of beer without paying anything for it. But then someone else comes along and also invents a perpetual beer-brewing machine. And then another, and then another. All of a sudden you have intense competition with prices approaching zero because everyone needs to compete with one another.
That is digital distribution in a nutshell. You have your inventor (the development team) who produces a beer-brewing machine (the intellectual property) and creates endless bottles of beer (the digital licences). It's the commercial pipe-dream - maximum profit at zero-cost production - but sadly, it's just that. A pipe-dream. It doesn't take in account price pressure and competition.
In reality, digital distribution isn't a 100% zero-cost operation. Bandwidth, servers and support staff all cost money. It doesn't take all that many sales for these costs to be recouped though, meaning that the value of each game is actually comparatively low.
Steam is an unusual situation in this respect though - significant amounts of the traffic on Steam's network is from non-paying customers. Judging by SteamCharts' figures, DotA 2 accounts for at least 50% of Steam's traffic, and there are also significant numbers of buyers from retail, GamersGate, GMG, Humble Store and other sites, for which Valve doesn't see a penny.
This is why I'm sceptical about claims of Valve's success. They post all kinds of useless information like how many supposed active accounts they have and what share of revenue comes from each country, but the silence about actual sales figures (together with the ban in distribution agreements on disclosing sales figures) tells me that they're not rolling in the moolah as much as people would have us believe.
Digital distribution really is a ticking timebomb.
(Sorry about the wall of text)