It’s a client request, the team and I have no preference, but as you know : the client is often king.
There are multiple reasons.
Our partners prefer the PDF certs. That’s what I’ve been told. Because also have courses on edx.org, they prefer the way the PDF certs are rendered when printed versus the way the HTML certs are rendered when printed.
We also allow for more than one logo because we do have courses with more than one institution and each one wants their logo on the cert. Also a lot a customization based on various details each course or each institution wants on their particulate cert. The same institution might have various templates depending if the course is for a specific target group ou a different language (French or English).
We slightly modified gen_cert.py in edx-certificates in order to “support” some of our clients/partners request in the past. Of course, most of these modifications predates the coming of HTML certs. When HTML came along, we did have a look at it but our management didn’t wan’t to go that way if PDF certificates were still available.
In the end, that might force us to review all our certificates templates and its processing.
But if I give in, I will be asked a lot of questions why I did…