The average person does not have much time (if any) to spend creating media and has patience for only a finite amount of choice.These kinds of tools are only suitable for early adopters, people who like to tinker and are willing to endure some level of suffering.
Bloggers and others who put a lot of time and effort into media consumption and media creation are outliers -- people may want something more customized than the morning paper, but they still want the simplicity and leisure feel.
Most people don't have time to do a lot of voting, tagging, saving, and commenting -- there's already too much filing and sorting to do at work and with the monthly bills. For the average person, media consumption consists of reading or viewing and then moving on to something else.
But most people are lazy. If you ask them to do a lot of work, they won't do it. As they see it, you're only of value to them if you save them time. And, you know what, they are right.
See also my previous post, "People are lazy".