Eventually people would run out of cocaine, and would become depressed and downtrodden. During these periods they’d greenlight or animate dark animated tales. Then they’d take the money from it and buy more cocaine.

Desperation, and lack of imagination. Disney had become gradually almost irrelevant in the years following Walt’s death, and they decided maybe it’s because they weren’t dark enough (desperation) and also because they weren’t cheap enough (lack of imagination).