No, I'm not saying any of the plays are failures, by any means. But I think it is worth remembering that many artists of all kinds, including Shakespeare, were trying to make a living from what they did. I have little doubt that there were times when he had a successful play running while knowing that it had a natural end-of-life approaching and so he had to start work on something else to be ready in, say, 3 months. Sometimes you can still achieve great things that way, but there's always the risk of ending up with something that is not as good at you would like. That's true now in theatre, and no doubt it was always true. It's exactly the same with the infamous second CD/play/book syndrome.

So in short: seek out and enjoy great plays/books/scupture/arts/song, by all means, whatever that means to you. The author will often be a good guide. But having that author is not enough to make it great.