And I think maybe it's because the 4e / 3.x split finally put out in front of us, in the full daylight of blogs, forums, and chat rooms, something that we had maybe suspected but weren't really willing to admit to ourselves---That when it comes to D&D, rather than being "united" in our game of choice, we'd actually been demanding radically different things from E. Gary Gygax's magnum opus all along. The fact that it remained somewhat of the community's "lingua franca" for nearly 25 years is a testament to Gygax's original vision.
One reason the 4e / 3e split was so divisive, I think, is because when the 4e fans threw up their hands in joy and said, "FINALLY!!! CLASS BALANCE!!", all of us 3e fans went "Huh? Really? THIS is the game you wished you'd been playing for the past 25 years? Hmm. Didn't see that one coming." The concept that entire groups of players would so wholeheartedly embrace 4e's conventions seemed almost foreign to the 3.x-ers.....and the 4e-ers couldn't for the life of them figure out why the 3.x-ers couldn't see that the mechanical improvements were producing a "superior" style of game.
As a community we were forced to look across the table, across the room at our FLGS, and realize that what we assumed was a "shared D&D nationality" was more akin to groups of isolated city-states battling it out for territorial control. (I realize some of the more long-standing gamers probably came to that recognition long before 2008.)