I think it's a valid reaction, and not limited to the RPG industry.
It's all about opportunity cost.
When Blizzard pours all their resources into WoW, if you're not a fan of MMORPGs, and are a fan of Warcraft, Starcraft, and Diablo, there's an opportunity cost.
When Joss Whedon spends a good chunk of time on a Wonder Woman movie that he won't end up making, there's an opportunity cost for fans of the Buffyverse.
When Robert Jordan delays finishing the Wheel of Time series while writing Conan and civil war novels, there's an opportunity cost for fans of WoT.
Back to D&D in particular...
When WotC announces that they plan on limiting the number of campaign settings they'll produce, and you're a fan of Greyhawk, Planescape, Dark Sun, Spelljammer, etc., and they go on to announce Eberron, there's an opportunity cost.
When one or more of your favorite designers are assigned to the new campaign setting that doesn't interest you (James Wyatt, I miss you), there's an opportunity cost.
It's all about opportunity cost.