That's kinda what WoL felt like. A constant stream of guest appearances used mainly for the 'Hey remember this guy? Huh? Huuuuuh?' It got in the way of everything else. It's kinda like D3's 'Hey remember this place? Huh? Huuuuuh?'
Hoping for something new from HotS, even if it's secondary to the multiplayer for me anyway.