Kids ain't readin comics like that breh.
The Avengers/Spidey have cartoons and games... and their cooler than the inhumans so..
I'm just not seeing it
They are cooler than the Inhumans to you. But--I say this with all due respect and no offense intended--this isn't about you. Or me, for that matter.
My point is, those same kids that will see the Inhumans in the movies, tv shows, cartoons, games, and so on...some of them will eventually read comics too.
Same thing happened to the X-Men. A lot of fans today got into them via the cartoons, games, movies, etc. From there, some of those folks eventually began reading the comics.
Besides, the big money for properties isn't really comics these day, its everything else. Especially the movies. The Inhumans don't have to be real big in the comic book world to be successful. What will matter is everything else outside of that, especially the big time stuff (movies, shows, cartoons, big name video games, etc).
You may not like the Inhumans, but Marvel is thinking long term on this one. They own the Inhumans property entirely. Why would they not push that, instead of pushing a property that they don't own entirely? Then you consider that Marvel and Fox's relationship as far as the movie rights are concerned hasn't changed and won't change anytime soon, so no Sony deal on the way either.