Hypothesis A: Successors to tyrants will be less fierce, because tyrants themselves fear fierce wanna-bee underlings.
Hypothesis B: Hereditary monarchy does not breed for love of power, therefore successors will become less fierce than the first usurper monarch. Bryan Caplan attributes this view to Gordon Tullock.
Hypothesis C: Any method of orderly succession is better than recurring contests for national leadership.
Hypothesis D: Over time orderly succession becomes difficult to maintain, given the lack of fierceness of the rulers.