Should Orthodox Judaism ordain women as rabbis? The Rabbinical Council of America recently said no, but not as a matter of Jewish law. Instead, it was in deference to tradition:
"Due to our aforesaid commitment to sacred continuity, we cannot accept either the ordination of women or the recognition of women as members of the Orthodox rabbinate ... The RCA views this event as a violation of our mesorah (tradition) ..." 
Other conflicts between law, tradition, and modernity are similar. Should Judaism welcome gay, lesbian, and transgender individuals? At a less controversial level, should Orthodoxy permit driving on the Sabbath? What about permitting ebook use on the Sabbath, as I personally wish it would?
I can't give you the answers to those questions. As President Obama remarked in a different context, they are "above my pay grade."
However, I can tell you that the argument from tradition is not just a debating tactic used by opponents of change. Tradition really matters, both when the issue is a matter of Jewish law and when it is only a matter of settled custom. Tradition makes a difference in people's lives.
The problem goes beyond Orthodoxy and beyond our present era. Zacharias Frankel (1801-1875), one of the founders of Conservative Judaism, stormed out of the Frankfurt Rabbinical Conference of 1845 because the Reform movement proposed abandoning Hebrew in worship. He identified the dilemma we still face:
“Maintaining the integrity of Judaism simultaneously with progress, this is the essential problem of the present." 
In secular law, the relevant doctrine is called "stare decisis" (pronounced "stah-ray duh-see-sis"). It advises us to stand by earlier court decisions unless (a) they are flawed, or (b) society has changed so much that they obviously no longer apply:
"The burden of proof is always on the one who wants to change the law, rather than on the one who wants to continue what it has been in the past." 
So the presumption is to follow established law or tradition unless there is a strong reason to reject them. Sometimes the reason is clear, as in the U.S. Supreme Court's Dred Scott ruling (1857) that African Americans could not be American citizens. Other times, the situation is ambiguous because there are benefits and moral arguments on both sides.
But why should that be? What's so good about tradition?
In isolation, nothing. But people plan their lives, invest their emotions, and form a sense of self and community on the expectation that things will not change too much or too fast. To reverse long-established traditions has costs for individuals and the community. In secular law, the costs are usually economic, but the same considerations apply:
"When the Court is deciding whether to overrule a precedent, it must confront the extent to which stakeholders have relied on the precedent in organizing their behaviors and understandings. That calculus is an integral part of protecting the legitimate expectations of those who live under the law." 
Shared beliefs, practices, and traditions also unite people, fostering a sense of identification and loyalty to each other. Those shared factors are a reason that the Jewish people have survived through millennia while mighty empires disintegrated and disappeared.
Big changes in law or tradition, even if entirely justified, weaken that bond between us. Then you end up with Orthodox Jews who deny that Reform Jews are really Jewish,  and Reform Jews who think the Orthodox still live in the 16th century. As sociologist Robert Nisbet observed:
"Society, Burke wrote in a celebrated line, is a partnership of the dead, the living, and the unborn. Mutilate the roots of society and tradition, and the result must inevitably be the isolation of a generation from its heritage, the isolation of individuals from their fellow men, and the creation of the sprawling, faceless masses." 
By all means, let's change traditional practices when needed. But let's not assume we can do so without cost. "Stare decisis" is a wise starting point for our decisions.
Dorff, E. (2011), The Unfolding Tradition: Philosophies of Jewish Law. Aviv Press, New York.
Nisbet, R. (2011), The Quest for Community. ISI Books, Wilmington, DE. Kindle Edition.
1. "RCA Policy Concerning Women Rabbis," Rabbinical Council of America, October 30, 2015.
2. Quoted in Dorff, E. (2013), loc. 1190.
3. Dorff, E., loc. 1206.
4. Kozel, R., "Stare Decisis as Judicial Doctrine," *Washington and Lee Law Review* 67:411, p. 418.
5. Kershner, I., "Israeli Minister Says Reform Jews Are Not Really Jewish," *The New York Times*, July 7, 2015.
6. Nisbet, R. (2011), loc. 799.