Yeah, that's what reminded me of this function. Though, this function could be abused by more "real" spammers which would also not leave much a trace on the server, compared private messages. It's not only that it might be annoying to users to get spam addressed as being by "chipmusic.org mailer", but if such a spam attack happens and a lot of people mark these e-mails as spam, this could also affect other forum e-mail like signup nd thread notifications e-mails.
So I figured it was a good idea to turn it off by default.

Has this something to do with a recent event?

In the interest of preventing spam, the function that allows users to send e-mail to other users is now disabled for all users. Users who wish to be able to receive e-mail from other forum members can still enable this function by going to profile in the top menu, then settings, select "Hide your e-mail address but allow e-mail via the forum." and update profile to save the setting.

This function is different from private messages, which are not affected by this change and work just like before.