IATA no longer charges membership dues to its airline members. They make their money by selling products and services. Although technically 'not-for-profit' that principle does not extend to its senior management who receive large bonuses on top of their large salaries and benefits.
They constantly need to come up with new money making schemes. What used to be free or at cost (to members) is a thing of the past. Their Dangerous Goods Manual costs a bomb (pun intended) but every office on the planet that sells cargo has to have an up to date one to hand.
This appears to be yet another attempt to separate money from the punters, via bag manufacturers.
But don't be mistaken, they are a trade association of the airlines. They don't give a stuff for the airline's customers; you and me.