It was not really a matter of enlightenment reasoning, but republican traditions that the Romans of their time would have been highly familiar with. Caesar had himself proclaimed "dictator for life for the purpose of reforming the state" only a few months prior to being killed, basically repeating what the by-then hated and vilified Sulla had done roughly a generation earlier (except that even Sulla had not dared to demand a
lifetime appointment, this was evidently Caesar's idea). This post on the ACOUP blog goes in more detail wrt. the legal implications of that kind of move, which by that time had become quite clear to the Romans themselves:
https://acoup.blog/2022/03/18/collections-the-roman-dictator...