Starcraft released: 1998
Starcraft II announced: 2007
Starcraft II released: 2010
It's been nowhere near long enough according to Blizzard time..
Sadly, you might be right. Their focus seems to be to create only games with lots of micro transactions or DLC. No new, complete IP since D3. And even D3 was meant to be a micro transaction game. They either had no idea how bad the RMAH was going to make the game, or they didn't care as long as they made money off of it.
It's really sad the influence Activision has have on Blizzard. Activision had some great games out a long while back, but now it's all FPS that I see. Mechwarrior 2 and it's xpac Ghost Bear Legacy are among my favorite games of all time. I still play it from time to time using DOSBox.