I don't hear anyone complaining about the pay disparity, that's because the pay disparity makes sense to the average person - as does the pay disparity between an NFL QB and the WNBA. The more money the business makes, the more money the players/models make. I would guess the difference in interest/money between the NFL and WNBA is similar to the average persons interest in female supermodels versus male models.

In some ways I understand the frustration if your on the wrong end of either of these, but you can't really make a good argument suggesting the wnba should be paying their players $16million. Best way to be sure it's "fair" is to look at the percentage of revenue each of the respective leagues pay out - I would be surprised if the WNBA players don't make a higher percentage of revenue than players in the NFL.

*Note: above numbers for model pay was based on an article in fortune about income in ~2014.