In place of the quote in my previous post, I might have written: “The main reason TSR/Wizards puts out new editions of D&D is economic: They are attempting to maximize the profits of the D&D brand.” Which is much more interesting. Is a new edition the best way to maximize profits for the D&D line as a whole?
A quick view of history might tempt me to say, “Yes!” I don’t think there’s any doubts that “third edition” increased profits over the end of the AD&D second edition era. The “fourth edition” books already appear to be (pre-)selling extremely well.
If Gygax is to be believed, though, AD&D second edition lost half the AD&D audience. It’s quite interesting that—due to demand—TSR did another printing of the first edition Players Handbook after second edition had been released.
Although the “fourth edition” core books are selling well right now, are they selling better than the “third edition” core books did over the same period of time? Will they sell better over their lifetime than the “third edition” books?
It’s a complicated picture, and you can’t really know since one path has been taken and the alternatives left untried.
There’s also that—and this is just my impression—AD&D first edition, classic CMI† D&D, and AD&D second edition were all motivated more by politics and royalties than by maximizing profit for the overall line. First edition was about getting Arneson’s name off the game. CMI D&D was to bolster the case that Arneson shouldn’t get royalties for AD&D. Second edition was about Gygax being gone. If those editions were less about economics and more about politics, then I think there’s a good chance they didn’t serve the brand well economically compared to other paths that may have been taken.
† CMI: The Companion, Master, and Immortal sets—and the rest of the latter day classic D&D line.