I understand that it's a big assumption to make -- that a benevolent AI could be constructed. But under that assumption, why not have a benevolent dictator in the form of an AI?
We already live in that world, with large institutional bureaucracies playing the role of paperclip-maximizing AGIs.
It's pretty wretched when you are in their path.
If the benevolent AI ruler(s) restrained themselves to allow for humans to flourish, then okay. Assuming it could be constructed benevolently.
With AI, it would try its best to preserve/enhance/spread itself forever. And its best might be much better than our best...
How much worse could it be?
If Skynet determines we're the problem (wars, famine, global warming, inequality, non-cooperation etc), I'm losing counter-arguments by the day.
But it's still a fascinating endeavor.