I get the reasoning behind it, but the fact is GW are facing more competition and a shrinking market in Europe due to the ongoing financial crisis. Even if people can continue to afford it they run the risk of alienating players simply by seeming irredeemably greedy. If these prices are US only it won't be quite so bad, but they really need to be doing more to boost sales beyond just finding the price the market will bear.
Of course if they are smart and notice a decline in sales ifter an annual price rise it would be nice to think they would drop prices but the worry is they would continue to raise them to mask the sales decline.