I think nostalgia is clouding peoples' minds, Starcraft 1 had a better storyline but not by much.
I'm not arguing Heart of the Swarms' storyline is good, it's not, but it does enough to keep you interested in the game.
Sadly Blizzard's writing has never been Pullitzer prize material, especially recently considering how often characters have been killed/resurrected in the Warcraft universe.
If you don't support small developers like this then don't be surprised when all you get is yearly franchises (Eg: Call of Duty, Assassin's creed, etc.) with draconian DRM.
PseudoElite's comments