first, thanks for your reply blog, Gerard.
On Sat, Jun 18, 2016 at 1:00 PM, Markus Kroetzsch
I have written
my opinion on the licensing of Wikidata data.. 
I agree with your position there.
So do I.
The original article ends with:
"Among all Wikimedia projects, Wikidata is conspicuously alone in not
Copylefting or not has been heavily and religiously debated for many,
many years in the open source community. I have never seen strong
examples why either would be better for open source.
Second, data is not text and is not source code. It's different and
"conspicuously alone" is a false argument.
"Perhaps we should start asking why that is the case"
Two possible reasons given above. Add to that what Gerard wrote.
"and whose interests benefit from weak licensing choices,"
No, that's the wrong way around. CCZero is a stronger license
(actually, it's not a license, but a waiver): it gives people more
freedom, removes many more hurdles.
"and start to organize ourselves to fix this"
There is nothing to fix. CCZero without copylefting gives more freedom
and for me that main reason to invest my time. Before you start
talking about "fixing", realize you will also loose.
(this is a personal opinion, and may not reflect the interest of my employer)