"By their nature these releases are unstable and should not be used anyplace where your data is important."
That's from the download page pointing to where the nightlies are kept. It is Beta software no matter how many people decide to use it on their "production" site. If you want to make sure that you get all of the latest information on those builds, you should be subscribed to the Beta e-mail list.
I'm not trying to scold you here or anything, but you cannot expect the dev team to make announcements to the general public regarding every change (even big ones) they make to alpha and beta software. That will all be made known when the official 1.5 release comes out. In other words, yes a "heads up" is too much to ask.
EDIT: I just wanted to add that I'm obviously not speaking for the developers here, just general beta practices. I've lost enough data in situations like that to know backups are essential.