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Bandai seem to have adopted the Sith "Rule of Two" and applied it to alternate heads/faces.
To use Star Wars as an example, if they were to make an action figure of the Emperor he would include a neutral face and a grimacing face. You won't be getting pic related, I guarantee it.
If they won't go all out on the best selling licenses, like Star Wars, what hope does anything else have? Is it really too cost prohibitive for them to include three heads/faces?