I know some of you are scratching your heads now but i know for 100% why they made this choice.
This is all about GamePass.
GamePass is basically Netflix of gaming. You pay 10$ (right now they have 1 month promo for 1$) a month and you get ALL new games from MS and licenses their acquire AT RELEASE DATE OF SOMETIMES EARLIER THAN THAT. Right now they have around 100 games and they included Forza Horizon 4 AT RELEASE same as Gears and their other exclusives.
But why exactly ?
Because with GamePass they need diverse games to catch all kinds of people.
You might be playing RPGs only for example so you get GamePass and not only you will get Pillars of Eternity
opamole Edition but also Forza Horzon, Forza, Gears of War 5, Halo5 and shitload of other games.
Gamepass basically forces them to make diverse games instead of doing only shooters.
They have right now promo. For 1$ you can get month subscription (no you don't need to buy 6 months) and play those 100 games as much as you want.
For example right now instead of buying FH4 for 60$ you can just pay 1$promo (10$ proper price) and play it.
https://www.xbox.com/en-US/xbox-game-pass