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One disadvantage of having a lot of classes, where there are sets of classes, each corresponding to a different facet, is that the information in the facets is lost and the class hierarchy gets large. Compare:
On the left, you have a flat list of subclasses with no information about underlying facets. On the right, I manually added the colors to show that they belong together. Using classifier, the hierarchy is much simpler, and each facet is very explicit and easy to see, understand and evolve. If there were just lots of classes, it would be harder to keep track of the facets.
The restrictions on LoanContract tell you what the facets are.
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All of this valuable domain information is hidden in the first approach. If there were just lots of classes, it would be harder to keep track of the facets. This makes the ontology harder to understand and thus to evolve. There is no place to go to add a new loan reason, say BoatLoanContract. Perhaps there is a way to add it?
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