>>What you are saying is that if any company provides a widely used product, say like Instapaper, they are ethical mandated to continue providing it, etc. Why would I create something for fun then, if I'm morally obligated to dedicate to it in the off chance it becomes popular? When can products close down?

If you want to close down a product, you can at least open-source it. Which is another thing Google could have done with Reader. It would have given another party the opportunity to pick it up and develop/maintain it.