The idea that IOA is a park based on literature is completely untrue. That was never the idea. The only thing IOA is based upon is "IPs that were available in the early 90s".
BTW, read Sam Gennawey's new book on Universal. It's amazing and has more information than you would ever need to know on the development of USH, USF, and IOA.
There are insightful stories, like how the designers originally wanted to put an island in the center of the lagoon in order to drive home the "islands" concept (it's an awkward idea at first, but once you really think about it, it makes wonderful sense). A Universal exec nixed the idea because he thought it's best to force people to walk the entire park without skipping anything, resulting in what the designers called "peninsulas of adventure".
Sorry for going off-topic. Point is: Anything fits in at IOA.