Things should only counted as a failure if the company lost money in that department. But fans care about numbers. Everyone wants each new system to do double the last. If that happend the PS3 needed to sell 240 million. And the PS4 needs to sell nearly 500 million. Not gonna happen. What's the most popular tv event in the USA. The superbowl.
100 million people watch it right. over 200 million don't care. Is that series a failure? It's all relative. What about all consoles. They sell lik ecrap, if you look at the planets population. It's the same logic with N64, GC, and even Wii. People hated them. But who cares? They brought in profit to the company. Not a loss.