You have dishonest and deceitful so-called developers out there to blame for this.
From a users point of view I agree with this change from Google.
There is nothing more annoying than an app that throws full page interstitial ads all over the place.
After every level, menu, at the start of a game, at the end of a game, randomly throughout the game, when the app opens, closes...
I mean it is getting ridiculous out there.
Probably 75% of the apps I have downloaded lately get immediately uninstalled because of this behavior. They simply are not worth my time.
I downloaded that popular game "Don't Tap the White Tile". Thirty seconds. That's how long it lasted on my phone.
After the first ad popped up in the middle of the game and I taped it by mistake...it was bye bye.