As someone who has volunteered in the past at a public aquarium, I can say that there is a certain ramp-up time for any major institution that lasts several years. Part of it is the systems maturing, collection building, as well as simply finding the right mix of fauna to display that will satisfy the average joe (where are all the Finding Nemo fish?), "hardcore" enthusiasts, as well as the goals of the institution (ie propagation and breeding).
Our aquarium (Aquarium of the Pacific in Long Beach) had a fairly unimpressive collection when it first opened, but over the years the collection has grown tremendously in both size and variety. During my year working there, the Aquarium organized a collection trip to Palau, New Guinea and came back with a bounty of fish and coral. Also, through trading and what not the collection has become more varied; displays have changed significantly to the point where I don’t recognize most of the displays from when I was there.
I’m assuming the same applies with the Georgia Aquarium and they are not just going to rest on being the biggest with the biggest fish.
BTW, nice pictures and thanks for sharing!