Earlier this month, Jack Dorsey (the illustrious Twitter co-founder who now heads up Square, the market leader for mobile payments) came under fire for a photo he tweeted that showed him lunching with Square’s crop of summer interns. The photo was rather unremarkable – a bunch of youngish guys sitting around a boardroom table with sandwiches. There’s a range of skin tones and ethnicities present, which is typical in the tech world.

And zero women. Which is also, unfortunately, typical in the sector.

The Twitter storm raged briefly, and a couple of tech-news outlets (BetaBeat and HuffPo’s Women in Tech) wrote about it, and then it passed. (It’s hard to sustain outrage about the skewed ratios at any particular tech company when the entire sector is so male-dominated, I suppose.) But while a few people offered constructive suggestions about how Square might infuse some gender diversity into its ranks (Anil Dash, for instance, proposed that Square get on board the Hacker School bandwagon), I didn’t see anyone talking about why Square should care. And that’s a big oversight – not only because I want tech founders to understand the benefits of including women, but because Square in particular has an enormous amount to gain from having women on staff, and in leadership positions.

(It’s worth noting that Square has a female CFO and at least one woman on their board, and Jack Dorsey has some real change-the-ratio cred. This isn’t an attempt to single them out for a unique lack of women in the company – it’s to point to the unique opportunity they have to benefit from having more women on staff than the average tech company.)

So, how can women help Square stay ahead of the curve & beat the competition?

1. The real sweet spot in their market is small-scale sellers. Square’s product is in use by the kinds of people who used to deal in cash-only transactions – everyone from cab drivers, to hairstylists, to artisans selling at farmer’s markets and craft fairs. Women-owned companies comprise 40% of all privately held firms in the US, and most of those are small businesses with revenues of $1 million or less per year. That makes women entrepreneurs a key target market for Square. And the best way to keep your company competitive is to keep up with your customers’ needs.

2. One of the best ways to win customer loyalty is to hire your best customers and turn them into evangelists. Etsy has figured this out: They make money from their sellers, so it benefits them to focus on increasing seller retention and help their sellers sell more. As such, they’ve hired many fomer sellers to work for them as seller relations experts. Square’s business model similarly relies on its customers’ sales volume – so if they can help boost their customers’ revenues, it’s a win-win. From their customers’ standpoint, working with a company that has people like them at the other end of the support line (or sales line, for that matter) is a more attractive proposition. Not only that, but if Square is really smart, they’ll seek out superstar customers in key niches and entice them to come work for them, as a strategy for recruiting & retaining customers; prospects in those niches will be more likely to trust a company that hires people they know & respect. (Hint to Jack Dorsey: Look for people who are natural community managers, like farmer’s market organizers, design bloggers, and crafters who share their expertise freely in online forums.)

3. The technical team is the product team, and the product must reflect the customers. I’d wager that Square, like many tech companies, already has plenty of women in sales and customer service, but few women in the engineering department. The trouble is that in tech, it’s rare that sales and customer service staff are involved in product design decisions. And when you’re designing for a market that’s at least 40% female, it behooves you to include some women in those decisions. The easiest way to do that is to recruit more women into engineering positions.

Here again, it’s worth looking at Etsy’s approach – although it remains to be seen how successful they’ll be. Etsy, as I discussed in an earlier post, is making a concerted effort (that includes financial backing) to get more women on their technical team – a smart move, given their customer base skews strongly female. Square would do well to take a similar approach, and get as many women as they can in product development roles. It would show a genuine commitment to understanding their customers’ contexts and needs.

In sum: Dear Square: When you post photos of all-male teams, you don’t just risk looking brogrammer-ish; you risk losing your competitive edge. Women love your product – and we want to see our perspectives and priorities reflected in the companies we work with. Get us on board, and we’ll help you go farther, faster.