I have to say, that in your 10+ years of gaming, you haven't played a lot of games. There are way more games, that are not alpha or even pre alpha (As DayZ SA is) and they got worse mouseinput problems. It's an alpha. They fix something and something breaks. That's actually pretty normal. I'm sure that they haven't tryed some kind of super-realistic-mouse-movement-simulation stuff. I suppose that they fixed something else that caused this issue. That's not scandalous. It would be, if they couldn't get it fixed, but I'm sure, the next patch will fix this issue.