I feel like it is obvious that this is not a normal circumstance situation. I don't think if we had a normal schedule we'd have these VoDs/Streams. Although this new trend starting with 8.2 and onwards have been a bit weird. I do like having stuff previewed as it is become pretty industry standard.
Fundamentally we also have no idea what they are showing off tomorrow. It could be just 9.2 and if so I agree you have a point, but if there's more and some sort of vision on the future of WoW statement it does make sense to have it in video format.
Regardless, I do think that we should try our best to return to a place where the x.1 -> x.2 drought doesn't mandate some sort of video response and instead keep the big announcements directed on Expansions. But at the same time I do feel since we don't get any other communication other than these Preview videos and the incoming Council it is really hard to guage what the right call is.
My genuine take away is that there should be other forms of communication than just these Previews and that we should step away from x.1 -> x.2 droughts that make the need for Patch previews a necessity. Obviously harder to work out than just pointing out the obvious, however.