I'm not so certain that the operating philosophy behind the Galactic Empire — that despotism is necessary to maintaining the peaceful cohesion of a galaxy-spanning empire –is entirely wrong...[T]he Galactic Republic — collapsed largely because it was too large to be effective. The Republic didn’t even possess the strength or legitimacy to handle a trade dispute on a minor core world, much less an existential threat like the Clone Wars.Bernstein responds:
Surely, that's completely wrong. The Republic wasn't defeated because it couldn't handle a trade dispute or the Clone Wars; it fell because it was the victim of a monstrous conspiracy by Palpatine.... [T]he trade dispute, the clone wars, even the petty infighting and jealousy -- were all just part of Palpatine's plan.Bernstein is quite correct on this, and also in noting that the Old Republic lasted for 1,000 generations while the Empire didn't even survive one. And it's hard to think of a governmental system that could have withstood Palpatine's treachery. He was an enemy (Sith) that the Jedi thought were extinct and that they couldn't even detect when he was right in their presence. It would be like if America suddenly had a president who was secretly a Communist... no, wait.
But it is worth noting that the Old Republic's successes came at a price. Near as I can tell from the films*, the Republic stayed intact largely by ignoring divisive issues like slavery. They mostly abandoned Outer Rim systems like Tatooine, leaving the local mafiosi in charge. And for a democratic republic, they seemed to place a great deal of authority in royalty. Okay, sure, Padmé was elected, but as a teenager, and for all her courage and beauty, she didn't appear to be a particularly skilled queen or legislator.
*Like Bernstein, I have not read the books, nor would I admit to doing so if I had.