They really didn't actively think it was a good idea. They changed the discovery tab to be a web page, which as the github repo linked by the OP will show you,

They really didn't actively think it was a good idea. They changed the discovery tab to be a web page, which as the github repo linked by the OP will show you, is now handled in the same repo (by the same people) as the AMO website proper. It was a mistake, and not as huge of one as people are making it out to be. As they have repeatedly pointed out, their GA contract makes it essentially a non-issue, unless you believe Google is so obsessed with tracking that they will violate their contract with Mozilla.