As Mitch "If my lips are moving..." McConnell implied in his otherwise stupendously cynical and dishonest response to the vote to reform filibuster rules, we must assume the reason it's never been done is because each side understands they could be in the minority someday and want to use it.
Fact is, the change affects only cabinet-related appointments and federal judges except the Supreme Court. Hardly a scorching of the process. Another fact is that over half of all nominees blocked by filibuster in the history of the US since the Constitution was ratified, have been blocked by Republicans during the Obama administration. Over half! I think it's safe to say, for several obvious reasons, not the least of which is, as opposed to teabaggRs, a belief in governance, that Ds would never, have never, and will never use the filibuster as regularly as Rs have since, well, you know...
So, good for them. Too bad they waited so long. Too bad it'll only affect a tiny part of R obstructionism.