Zerg isn't the least favoured race by a long shot. Most of the pro Zerg players haven't adapted to the new meta game is all. Life took Ling Bling Muta, an old WoL staple and dominated with it. He used Vipers a few times and even had a couple of Infestors in a few times. When I say simple play - it was focused, he wasn't trying out all crazy strategies or anything he wasn't comfortable with. He just went with what he knew has countered Bio forever. Saying that it was a simple play doesn't insinuate that it was easy. That's two very different things. He also defended his mineral lines effectively, whether with static defences or queens and a few units held back, denying the so called 'OP' Medivac boosters any benefits - something that most Zerg players didn't even attempt, leaving themselves wide open to have their economies crushed.
Most of the other Zerg players fell down because of a lack of static defences and a confused mid field play, which was more about stalling the Terran than trying to pressure him.