Blizzard was never really creative. Starcraft was supposed to be a Warhammer 40k clone, Warcraft is generic Tolkien fantasy and Diablo was just a D&D Rogue-like.
They originally started out as a graphic design studio and managed to popularize obscure genres by making them more "cool" and accessible. Using their newfound piles of cash, they went on to make products that are now nothing more than nostalgia bait. That's about all there is to Blizzard's "creativity", especially at the moment.