Agreed. The architect/designer lived about 10 minutes from me but he passed away in 2015. I always wanted to ask him this question as to "why" but never got a chance. The best explanation I have been able to find is this:
Graves chose a swan and a dolphin on purpose, creating two characters not yet used by Disney. The dolphin was inspired by the work of Italian sculptor Gian Lorenzo Bernini. An example of these dolphins can be seen at the King Neptune fountain at the Italian pavilion in Epcot. The major difference, however, is the dolphins in Bernini's work all have their mouths curving down as if they are frowning. Michael Eisner, CEO of the Walt Disney Company, insisted the dolphins were not to be displayed this way on Walt Disney property, and so Graves' dolphins have their mouths curving upward to give the impression that they are smiling.
His basic concept for the Dolphin was that it was an island formed by a sudden cataclysmic event—an upheaval by an underwater volcano or earthquake. When the island emerged from under the sea, it lifted dolphins out of the water, and these are the dolphins on the roof. The banana leaves on the side of the building are the tropical plants growing on the island. The mysterious “black box” was
never intended for monorail usage; it was the heart of the island, which burst open from the sheer force of the events. Water went spilling down the outside of the building into that “dolphin fillet” [two-dimensional dolphin] pool, and then splashed over to the Swan. The railings and the curving landscape connecting the two hotels indicate waves moving from the Dolphin and splashing up along the side of the Swan. These are the waves that you see on the side of the Swan. Two swans were so entranced by this natural phenomenon that they alighted to watch it up close—and were turned to stone.
Edit: Sorry Rteetz...just saw your comment. Will stop.