I think what has happened with Julian is that enough people were able to get him. A year ago at this time (January/February 2014), he was so heavily sough-after with selling that, I think, eventually people from that period (who are still active here) succeeded in getting him.
Though this has nothing to do with the purpose of Hound00med's list, I would love to see a hamster crack the Top Tier because, frankly, they're very cute. I have generally considered the deer to be the best-looking specie cast in "Animal Crossing: New Leaf." The hamsters are unheralded. The likes of Apple and Flurry are really popular here; but, Graham, Hamlet, and Rodney are also really good. And Soleil has this eccentric design that is not forgettable. (They're a new specie design for the "Animal Crossing" series with "New Leaf.") So, that's six of the eight already. Not bad. I'm more impressed with the cast of hamsters than the bulk of the 22 cats and 14 dogs. (That's just … me.)