Let's Encrypt just announced it
Wildcard Certificates Coming January 2018
Let’s Encrypt will begin issuing wildcard certificates in January of 2018. Wildcard certificates are a commonly requested feature and we understand that there are some use cases where they make HTTPS deployment easier. Our hope is that offering wildcards will help to accelerate the Web’s progress towards 100% HTTPS.
Not absolutely necessary but still a nice feature to have for certain specific cases
(cough cough ... subdomain hosting when you don't know in advance which subdomain will exists )
I'm gonna sound like a broken record, but again ..., if you don't have your server setup with HTTPS and also IPv6, you better look into it as soon as possible.