Is the Filibuster actually PROTECTING majority rule?

[bondwooley]

Tim Murphy has an interesting post on Mother Jones that explores a different point of view of the filibuster - at least a different view than the one I have, which basically categorizes the filibuster as a form of cheating any bullying.

Murphy's subject argues that since the Senate's composition does not reflect a proportionate constituency(highly populated states having as many votes as, say, South Dakota), there's no such thing as majority rule in the Senate to begin with:

It's not clear what majority rule means in the context of the Senate. The Senate's one of the most malapportioned legislatures anywhere! On the one hand you can tell the story where a bare majority of the Senate represents a very small proportion of the American population. And then the counterargument is that 41 Senators representing an even smaller portion of the population can block legislation. Either way, the main point is that the Senate is a very malapportioned body...so the ability to muster a majority doesn’t necessarily mean that the national interest is being served.

The full article is here: http://motherjones.com/mojo/2010/04/world-without-nuclear-options

What's the DU opinion? Is the filibuster a way for the minority to block the majority? Or since the Senate is not proportionately representative, is it merely a ritual that balances power and opinion?