Koger, in a piece entitled "The Rise of the 60-Vote Senate", explains not only the history of filibustering but also where we stand now. He writes:
"The modern Senate is dramatically different from the Senate of the mid-twentieth century. While senators valued compromise and cooperation, the default practice was that a simple majority was sufficient to pass
legislation. Filibusters were rare and spectacular exceptions. Now the default assumption is that a cloture-sized majority is necessary for any action. This system empowers legislative minorities to pursue a range of interests. Some proposals are blocked by filibusters, but others are forced onto the legislative agenda by minority hostage taking. As a result, the Senate is a less efficient chamber than the U.S. House, but it is also likely to discuss and vote on a wider range of issues than the House will allow."
The full text of Koger's piece is below. It's a fascinating read.