The blog seemed to be popular, and even players who disagreed with their being nerfed seemed to appreciate the fact that we tried to give some insight into what we were thinking. GC and the his crew are going to try to keep making similar blogs for every patch. I think it was one of the more positively received blogs in long while.
Offering a lot of justification for changes early on a patch though is challenging for a number of reasons. First is that patch builds are often just snapshots of the data at any given time. We wait until everything is near perfect for actual releases (as far as you can ever do with as complex a game as this), but when we are in PTR mode the devs are trying to get builds out quickly. That means you'll often see a change that was half-implemented or something that a designer was messing around with. There often isn't justification for those type of changes -- it could just be trying to fix a bug or seeing how something feels with a slight redesign. Second, it takes a lot of time to justify those changes and designers are often really busy implementing the actual changes at that stage in the beta. When the changes are not even necessarily 'real' changes, justifying what might not stick probably isn't a great use of time. Finally, we greatly appreciate feedback from the community and it can have a big influence on our game design, but at the same time we want to avoid the perception that the players are collaborating on with us on designing the game. It's tricky to manage expectations in that way, but if we lead players to believe they have more influence on design decisions than they actually do, then there's a lot of undue frustrated and dismay when we don't make a change that some may really wants us to make. Being able to take player feedback while making sure they don't expect that feedback to be implemented as-is can be a tough balancing act, but is still a necessary one.
In regards to your point about "trying to fix a bug or seeing how something feels with a slight redesign", this is EXACTLY what a large amount of the playerbase would love to hear. Just to say "we're testing this, we want to see what impact it has." Or if we see "we saw there was a bug with [x], so we're seeing if [y] will compensate for it."