1. those are big first party games.
2. I don't see why not. After a certain period of time they've made as much as their going to make, why not put it on steam. As long as it had a long enough exclusive period.
The way for MS to really fight steam is to compete on features first and for most, exclusive's (timed). Get the store and UWP to a high standard, then people won't be so relucent to buy from MS store. They seem to be working on all the issues people had with UWP.
I know people are saying they only doing it because it was a sales failure, but I think they would've anyway, it was always the plan. Like TR.
I think this is good for QB, MS, Remedy, gamers, and steam. Putting it on steam is almost like when a game gets put in bargain basket.