Clearly some people prefer to know in advance, to make sure they're prepared to patch critical servers on that day, and perhaps even take some offline until then.
It's useless because I don't know if I need to care. Vulnerabilities in openssl are nothing new so as far as I know this is just par for the course, and I get nothing out of it as of yet.
So what do you propose is the alternative? Not tell you about the vulnerability at all until a patch is released? Publish all the details about the vulnerability before a patch is available?
Clearly some people prefer to know in advance, to make sure they're prepared to patch critical servers on that day, and perhaps even take some offline until then.