This has nothing to do with some bracket not being merged, do you think they woke up one day like "ok so lets merge 19, no exp, let's half merge 39 no exp, lets fully merge bg exp all brackets" etc no, and NO.
Every bracket, of every level, of every exp state, of every battlegroup is merged... it's not working, why ? simply the way it has been designed, the way the matchmaking is being done, because it's not based on queue time anymore, the battlegroup you are on, give you certains priorities etc, they try to queue as many people from the same battlegroup and/or datacenter as possible, because it's all about latency issues nobody knows how they programmed that stuff but they don't have a magical miracle recipe...that make the latency question vanish... Yes you can fight people from the whole Europe, but no you can't play with and against people scattered on all europe, at the same time, on one game.
Hell I'm gonna jump my ship now saying that maybe they even check the latency of each players in the queue, and if it's not satisfying, bim bam, no pop... nobody has any clue how the damn thing works, so how can anybody dare say it's not working
Don't expect them to change anything from the core code, for who ? "a tiny portion of the player base" like they called it, in the risk of screwing all the Cataclysm launch and rated battlegrounds, you are dreaming, it's not gonna happen...
For me (and blizzard btw) it's simple, if the bg exps are working, and 19's non exp are working, end of debate the whole thing is working, not the way we want it, but there is limitations on the system...
So no need to run in circle and make GM tickets, btw GM are at the bottom of the whole thing, we know more than they do, and you asking them anything ? they barely have some superpowers not superknowledge