You'll find a lot of folks out there decrying the dumb stuff to be found on the internet. Absolutely -- like everything, 90% of the internet is crap.
But what people miss when they talk about the idiocy of Twitter or blogs or whatever is that you get to choose what you read therein. You could send a Martian into any bookstore and they'd conclude that books are mostly awful, because awful dominates in terms of sheer volume -- self-help, diet, celebrity, cash-ins, etc. We don't think of books as a sewage pit because we know we don't pick a random sampling to read, but make informed choices based on what we want to read. And within the range of things we might want to read are more wonderful books than we could consume in a lifetime, even though that range constitutes only a small sliver of the pie chart of books the market produces.
If, like me, you experience in the internet mostly through a feed reader, the internet looks very different than it does to the doomsayers. I subscribe to interesting sources through Google Reader, then flip through the hundreds of documents it serves up daily for me using the fantastic iPad app Reeder. In thirty minutes I can discover two essays I want to use in class, useful advice, cogent perspective on current affairs, inspiring and sobering personal stories, and a good laugh. If I see something I think deserves wider attention, I hit a button to share it with folks who have chosen to follow me; similarly, many of the items I read are those my friends have passed along by hitting that same button.
Seen through my screen, the internet is a place that enriches, informs, and entertains me every day. I choose to filter out the crap. You do, too, every time you watch something you've DVR'd rather than flipping channels, every time you go to your favorite author's shelf in the library, every time you refrain from sweeping everything from the grocery store endcap display into your cart. More choices always means a gross proliferation of crap, but that's not the important factor on which to focus -- instead, it's that we develop better tools for keeping our personal consumption nourishing, and watch the miniscule sliver of the pie that we want grow along with the part we're happily ignoring.