People weren't necessarily stuck on the Voltron idea, it was just one of the more popular and entertaining theories. It was announced like half-way in the build-up that the monster would be a unique monster invented by JJ Abrams, so theories quickly started centering around the plot and worldbuilding from the various ARG sites they had up. THOSE were far more interesting and fun than theories about an IP monster, Slusho and Jamie and the deep-sea drilling and all that other shit that went absolutely nowhere.