Whilst I agree the MS store is bad enough, what makes you think these will even come to PC on any store?
"Some of the teams are going to have games that will come out soon and have some things in the works, but mostly we feel really set up to give our fans new exclusive games for Xbox and a great pipeline of new things going into Game Pass"
https://www.youtube.com/watch?v=xAcjSQvdDq4&t=4m19s