I'm an economics major, so when I presented at the Women's Game Conference in 2005, I discussed the economic impact of diversity: reduced recruitment costs, increased staff motivation, increased creativity, and greater growth in new initiatives. A more diverse workforce means more diverse backgrounds and experiences, which can lead to richer ideas and greater community connections. Moreover, studies have shown that when the male:female ratio is more even, employees feel that it is a more pleasant work environment and this leads to higher productivity.
So why is it that there are fewer women in the game industry? #1reasonwhy has shed some light, citing reasons from misogyny to harsh work conditions to unequal pay. The prevailing economic thought on women's unequal pay when I was taking Labor Economics in college had to do with the fact that women can have babies. Because some women had babies and chose to drop out of the workforce, it was reasoned that employees could not count on women to be reliable. Therefore, it was riskier to hire women. Also, those women who did drop out of the workforce tended to do so during years when men were climbing up the corporate ladder so they lost valuable time in their careers. Often times, they could not return to the workforce after a hiatus.
However, the 2000 Nobelist in Economics James Heckman, who conducted a exhaustive study on women in the workforce, concluded that there was no "typical" woman who dropped in and out of the workforce. There were women who worked all the time and there were women who didn't work or worked part-time or seasonally. He concluded that companies should pay attention to the women who worked and invest in them equally. An unequal wage to a valuable employee would only be detrimental to the company and to the industry.
Of course, as many HR managers in the video game industry might tell you, it can be challenging to find a diverse pool of qualified applicants. It takes top-level commitment. See the video below for ideas on diversity initiatives.