So, 36% of the forum thinks Nova is average or worse and 23% of the forum thinks Supernova is average or worse? I have a feeling inexperienced players are voting without reading through the posts.
Also, sometimes "Better than average" cards should still not be nerfed because they are beneficial to the metagame. for example, RT is definitely above average but is important as a counter to Nova and Supernova. Fractal, for example, is important as a counter to Firestall that is also useful against other common decks.