I always assumed that was 99% of the reason there isn't a "WIP patch notes" or some kind of specific roadmap for SS. They can be good at making hype for the community but the emotional impact on the devs in having to commit publicly and manage expectations regarding content and timeframe is a huge downside. For sanity and making development pleasant, better to wait until somethings been done to talk about it on the blog or forums.
Holy *** just yesterday I listened to the Space game junkie podcast with Alex again since I was bored and there was a question on why isn't there a roadmap. He said something along the lines of there being constant changes in his vision so it wouldn't make sense to set things in stone. Which I agree with and always say ''Only way to make your plans not fail is to not have plans in the first place.''
Btw to your first point, there had always been WIP patch notes here as long as I've been following the game, so it wouldn't be something new.