Argument: Filibuster has been restricted; not enshrined in tradition
Timothy Noah. "Abolish the Filibuster!". Slate. February 1, 2005: "wouldn't abolishing the filibuster go against tradition? Well, yes and no. As this U.S. Senate Web page explains, the filibuster has been around since the beginning. But the trend over the past two centuries has been toward restricting its use. The House allowed filibustering for awhile, but got rid of it as its membership swelled and the need to restrict debate became more urgent. Before 1917, when the Senate first imposed a cloture rule, there was no way to stop a filibuster. (No wonder we had to fight a war to end slavery!) And in 1975, the Senate sensibly reduced the number of votes required to end a filibuster from 67 to 60. The logical next step is to get rid of the filibuster altogether."
Jean Edward Smith. "Filibusters: The Senate’s Self-Inflicted Wound." New York Times. March 1, 2009: "In 1917, with two-thirds of the Senate having been elected by popular vote, the first dilution of the absolute authority of the filibuster was achieved. The Senate adopted Rule 22 to permit cloture to be imposed (limiting debate) if two-thirds of the Senate agreed. The Times wrote, 'It is difficult to overestimate the importance of the new rule, both in measures of immediate interest and on the general course of legislation.'"