Caesar did not intentially seek out to destroy the Roman Republic, though his actions certainly sowed the seeds that brought about its end.
Caesar was, for the bulk of his life, committed to Republican governance and did what he could to work within that system. He was, however, an exceptionally talented man, and thus was opposed--often unfairly--by others, some motivated mainly by jealousy (Drusus), some through absolute opposition to any change whatsoever (Cato). Caesar could see that a government initially designed to run a city-state needed to change in order to run an empire, but many opposed him and his proposed reforms. So he resorted to force in order to put his changes in place, but he still considered himself a Republican.
You might see it as a case of "do as I say, not as I do".

Still, Caesar never had himself crowned king, which he easily could have done, so that's something.
As for becoming a dictator, that was entirely legal within Roman laws and its constitution; in times of crisis, other leaders of Rome, such as Sulla, had also been appointed dictator, so that wasn't unusual and in and of itself did not and would not destroy the Republic. In fact, there are parallels between ancient Rome and modern Turkey in this regard, but I digress.
To me, it's Augustus for whom Representation makes no sense as a favoured civic. While Julius often forgave his rivals and tried to bring them back into "his" government, Augustus had his opponents proscribed, exiled, and so on. He took Julius' changes to their logical conclusion: an empire, in that day and age, could not be run properly by a republican government that was often paralyzed by internal power struggles that frequently broke out into civil wars. Under Augustus, the Roman Republic truly came to an end, the Senate little more than a rump to carry out the emperor's wishes. Still, Augustus was smart enough to pay plenty of lip service to the Roman Republic, so I guess that's where his favoured civic comes from--but Police State or Bureaucracy would make more sense for him.