While we can only hope for a fix for the pet pathing issues during the overnight patch, I can say that at least a friendly neighborhood GM has replied to my forum post on the topic.
My question described the issue, and then asked:
I'm both reporting this as a bug and also asking if the devs are, as far as blues know, aware of it; also, was this an intended change?
The GM's reply:
Well, both actually. Our developers have been tweaking pet pathing in recent weeks to try to improve it in certain terrain. So, its current state is indeed intended, but our developers know that it is not in a great place right now and have re-entered it as a bug and will continue to work on it until they are happy with the way the mechanic functions.
It sounds like--on the first read-through, anyway--they tried to fix some bizarre pathing issues and screwed up, completely borking the way pet pathing works. It's also possible, though, that they were trying to make pet pathing more user-unfriendly, as a way to make the class more challenging, and they went too far. I am 90% sure that it's the former, and I certainly hope that I'm right. Perhaps when the servers come up we will see!