In a perfect world we would all have time to read every change-log of everything we are using but we can't.
but do we really need to be aware of all changes and keep track of them?
most regular users won't even know about most changes ever. for example they may not even know they are using PSBT, the wallet does that all for them.
as a developer it may be needed but keeping track of changes isn't that hard specially if it is a popular project and has many contributors.
If it involves money, yeah.
If this was an open source chess project and someone did not document a change and something stopped working then so be it.
With something that involves money, then yeah lots and lots of notes / comments / documentation.
It's not just PBST, it comes back to something achow101 said:
w.r.t BIP 174, it could probably be changed to final status. But Final also implies a finality and that the BIP won't change. However BIP 174 does change from time to time, especially as new fields get added to it. It makes me a little uncomfortable to have it be Final but then still add things and change things in it.
If it's final and never touched again, it's one thing. If you make a change and I am doing something and don't notice what you posted that's on me.
If you make a change and don't tell people about it, that's on you.
-Dave