The ultimate goal here is not to build a company with perfect representation of the general population, but to build a company which honestly evaluates and rewards the contributions of all its employees (because we believe that those kinds of companies do build better products, businesses, etc.) and you can't do that unless you're inclusive and consistently fair with everyone in the company.
A number like 50-50 gender balance doesn't mean that we've finished building that company (and no company is ever finished). However, an imbalance of gender or any demographic such as age, race, prior work experience (such as government, enterprise, startup), academic background, parental status, etc. at a company usually indicates that there's a blindspot or bug in a company's hiring or culture and it deserves a closer look.