Men overwhelmingly constitute the corporate world. Even in female led companies and institutions, the the more senior roles become more male. As with any major business decision or culture shift that requires buy-in from leadership, it's essential to have the men in the company on board. That’s just common sense.
Since men often are those who have the most experience and because moving up in any kind of hierarchy requires both personal relationships as well as mentoring and sponsoring. It's vital that men play a role in helping to support the advancement and professional development of women. If that's left up solely to the few senior women, it's never going to happen.Additionally, studies show that when men are engaged with D&I efforts in their workplaces and communities, everyone is much more likely to report that their offices are inclusive. (source)