With Blizz's focus on WoW, I can see why 1.10 took so long to come out.

Basically, they were patching the game to what would more or less be a 'Final Form'. Something they could put out, and basically not have to upkeep much. It seems to have worked fairly well.

I'm not justifying the year wait since the announcement, but how long did WC3 take? I think I was waiting for it for...7-8 years. Too bad I didn't like it as much as WC2.