Hello there,
While is true that previously some lettered releases have had some extra content, it was content that was thought out after the release and was implemented together with bugfixes. The "As for the 'more content' a lot of it has historically been catered to a very small minority shouting loudly on discord to have it" is not really true, everything is taken into consideration if it makes sense and Kal himself wants to add the content.
I can 100% understand that some people might feel uneasy about the development taking this long, which has never happened to this scale before BUT there are things that are not really right, the developer of anything has full control over the decision of how to release the content that is being worked on, there is really no need for an answer for "why all the extra content couldn't just be in another update?" as it was decided to be done for 1.9 to reduce the time needed to add such content and polish near the steam release after 2.0.
Some work has been shown of what's to come without giving spoilers, and some reworks have also been shown, is not like there has been full radio silence since the last update. There are people that say the last update was last year, even though 1.8B (yes, is a lettered update for bugfixes, but it also included a decent amount of content) was around 4 months ago.
This part I don't see how it comes to be a point "If there were at least some more explanations/updates or teasers of what is actually coming". Again, yes, the deadline for the given estimate release was missed, but an explanation, and teasers were given.
Also, on the topic of people that might worry about the update, I can understand it maybe from a newcomer, but most of the complaints come from people that has seen previous updates, that have seen work has been done with Starmaker and that has been advised WON'T be abandoned and will be finished with the 2.0 and steam release updates.