There are two main reason I see that WotC won't backtrack (plus a bonus secondary reason).
1) Marketing - Hasbro is the #1 seller of toys in North America and quite possibly the world. If you've noticed, they re-release successful lines (Transformers, GI Joe, My Little Pony, etc) about every 4 - 7 years. As WotC is a wholly owned subsidiary thereof, it makes sense that they too would follow this business model.
2) Money - following on the coat tales of 1 above, the reason for this is continued positive cash flow and a replenishing revenue stream.
B) Pride - I can't imagine any company going back to an older product other than Coca-Cola, and even they balked at it for a long time (New Coke was out and in production for 3 years before it was finally pulled completely.) Newer is always better in marketing regardless of proof to the contrary, that's why we have those nifty catch phrases like "shifting the paradigm", "wave of the future", "redefining style/class/precision/etc. and "raising the bar". Marketing research folks are a sad combination of yes men and scientists, however, they are for the most part, VERY effective at either guessing the next trend or forcing it upon you without you noticing. Either way, they are the rudder what steers the boat. And when it's all said and done, if the first two reasons are covered, then they can be forgiven by the board of directors.