While I agree that information generally falls into the important and unimportant categories, I disagree that these neatly map to "mange it" and "don't bother". This is because important and unimportant are relevancy questions that are in the mind of the seeker, not the corporate compliance officer. Sure, there are hard rules about some kinds of content (SEC filings for example) that mandate ECM services. But the vast amounts of information we're producing now benefit from being wrapped/referenced/tracked and otherwise brokered by ECM services. Information re-use, persistent referencing, mashing up, de-siloing, and distribution also drive the ECM value prop for E2.0 content.
In the interest of disclosure I have a stake in ECM so would naturally like to see unstructured E20 information brokered that way.