[pbadams]

Apart from the comments you've already gotten, another goal of geospatial systems is to support range queries (e.g. for the bounding box of the user's screen, what are all the businesses in that box). In higher dimensions range queries are mostly useless and the focus is on NN queries.

But as the other comments have mostly said, it's mainly dimensionality and scale differences that drive the design differences (e.g. graphs end up working better than trees in high dimensions)