Why on earth don't majority Democrats hand minority Republicans telephone books and tell them to start actually filibustering? It is only a gentleman's agreement that invests the threat of a filibuster with the full weight of an actual filibuster. So long as Republicans choose to turn every vote into a 60-vote cloture issue, Democrats might as well require them to own up to the mechanism that makes this obstructionism possible. At zero cost the Republicans can currently threaten filibuster on any legislation that comes down the pike; at the cost of reading from the encyclopedia all night long, some of these threats will surely be proven to be bluffs. Better yet, an intractable press will have to take notice when Republicans are forced to make a circus display of torpedoing popular legislation. Also, what the Democrats are doing now isn't working: Popular legislation is not passing and Democrats are being tagged "ineffective."
Many Republicans asked this very question when the Democrats were the ones doing the filibustering. The answer, as I understand it, is that if you make the opposition stay and actually talk, you (or a fraction of your majority) have to stay and actually listen. The spectacle is entertaining, but everyone would rather be home in bed, so they "let's not and say we did" became the order of the day."
Incidentally, is anyone else amused by the lightening speed with which filibustering has gone from [undemocratic obstructionism/a vital institution for protecting minority interests] to [an important tool for preserving Federalism/an obscene mechanism for thwarting the clear Will of the People]? No one's even bothered to come up with a better fig leaf than "but it's different when my guys are in charge!