Overwatch's skin distribution is, in one word, lopsided. With a roster of 54 heroes and counting it can be hard to ensure that every character gets their fair share of cosmetics as is, but when you add popularity into the mix it gets even harder.
As a free-to-play game, Overwatch makes the bulk of its money through cosmetics like bundles or standalone skins. Skins also take a good amount of time to prototype and create, so to ensure its efforts aren't wasted the team needs to pick heroes based on how many players will actually buy the end product.
