Spending many millions of dollars to transport a popular, successful, classic ride 6 miles south, with no viable return on that investment, to access land that isn't even on the list for expansion because several practical pads already exist elsewhere in the area isn't exactly a "no brainer" in the traditional sense of the phrase . . .Because it’s a no brainer
The pathway between Pan and Small World could stand to be widened, sure, but Small World does very well by its real estate. The land behind it is no more appealing for expansion than that behind any major attraction. Why spend ~$600 mil on Small World demo, relocation, land reclaimation, and then whatever you'd build in its place, when you could just drop ~$200 mil on a new ride on an actual expansion pad and spare yourself all the headaches?