There's like 20 Warhammer games that come out every year. None of them are good.
Probably more on both counts. And while you're right that the vast majority are either mediocre Warhammer skins slapped over genre-games or outright bad, there are quite a few gems in the pile. GW's has taken a shotgun approach to handling their licenses for video games. Basically no developer gets the rights to an entire franchise, they all get little slices. They either get a smaller title (Necromunda, Mordheim, Underworlds, Battlefleet Gothic, Space Hulk, etc) or they get a very limited collection of races to choose from. The only real exceptions to this are Total War (which, to be fair, is working off of a GW IP that is effectively "dead" since the publication of Age of Sigmar) and Dawn of War (which only got more races via expansions, and is now a functionally dead video game franchise after DoW3 flopped). But every other GW title gets little slices of the IP to work with, and if the developer does well, they get bigger and bigger pieces of the pie. They are fully aware that 80% of the titles will be bad or forgotten, but the 20% that hit will be well worth GW's effort.