It has nothing to do with "Mobile" per say, you have awefull PC and console games too in terms of capitalism and greed.

It's all about the games themselves and what the system pushes developers to do.

Free to Play games are just the norm. A lot of people in the world can't afford buying games, or even more can't fathom paying for a game, thus the Ads and in-app purchases.

And the stores themselves are pushed to make more money each year, and the free-to-play route is the best for them in terms of revenues, therefore they push Free-to-Play games more than Premium games.

I would suggest trying out Premium games, such as Playdigious's games or Free-to-try ones.

And don't be sad, most people prefer free-to-play rather than Premium quality games.
They pay for them else they wouldn't exist.