Why did the awesome creatu such as Kioka and Omni and Liyure retire? It's a real shame as they were so awesome.

The Kioka and Omni were the first Creatu made available in the Credit Shop, and they wanted to start putting more in there to give us more variety. Liyure were released shortly after the announcement that Kioka and Omni were being retired from the CS. They were retired to increase the value, and to even out how many are on the site. If they were still available, they would be worth as much as the newer ones, which just isn't a far trade, since most of us got ours quite some time ago.