Because it is important that everyone understand that SSL is dead and TLS is the replacement. SSL/TLS is forgivable, saying SSL is sort of like writing a headline “How this company uses VHS” when you actually meant Betamax. It’s misleading.
When talking to management, I try to avoid the acronyms (SSL, TLS, HTTPS, etc.), and in this case, I've coined a phrase that I find be equally understood by management, devops, and sysadmins alike. I tell them that we need to "encrypt server X with a secure certificate" (or "secure cert" depending who I'm talking to, which is as short as the shortest acronym syllable-wise). It's vague enough to cover the spectrum of acronyms in a timeless (for the foreseeable future) way, but unambiguous enough that everyone understands.
