krysaia tells us why: "Basic Account is an option available to accounts which were created before March 12, 2008. No account created after this date can be turned into a Basic Account."
Limit reached: Support volunteer intrepia adds that "the cutoff is that accounts with a userid below 15136000 can convert back to basic." This limit has been reached some time on March 12.
Paid time running out or opting out of Plus: what happens? When your Paid Account expires or when you opt out of the Plus level, your account will revert to the type you had beforehand. If you went from Basic to Paid/Plus, you will revert to Basic. If you went from EA to Paid/Plus, you will revert to EA. If you went from Plus to Paid, you will revert to Plus. If your user id is below 15136000 you will then be able to switch to basic. Your user ID's on your profile. It's the number next to your username.
Not seeing the same text on the FAQ: some of you may see a different version of the FAQ quoted above if they're viewing the site in another language than American English (because volunteers haven't had the time to update the FAQ in their language). So here's a screencap.
Statements from the LJ Staff:
[x] A statement from Jason Shellen, VP of Product Development for LiveJournal.
[x] Another statement has been posted in news.
Reactions from members of the Advisory Board:
[x] Brad "advised against this" but "hadn't heard anything recently about it.".
[x] Esther Dyson, another member of the Advisory Board, says she wasn't consulted either.
[x] danah boyd's reaction: "Needless to say, Brad's pissed. I'm pissed. Not only because we both vehemently disagree with this change, but because they made such a change without consulting us. Or rather, we were both at a lunch a while back where they asked us what we thought and we both told them that this was the worst idea ever, although for different reasons. I had thought it had been tabled until I learned of this. After it had been posted."
Feedback: SUP's contact page and Jason Shellen's 6A and LiveJournal, Inc. addresses if you need them.