I'd actually argue that we've had significant portions of our lives under the control of an inscrutable superhuman artificial intelligence for centuries. This intelligence is responsible for allocating almost all resources, including people's livelihoods, and it is if anything less virtuous than humans usually are. It operates on an excessively simple value function, caring only about whether pairwise swaps of resources between two people improves their utility as they judge it to be at that instant, but it is still observably the most effective tool for doing the job.
Of course, just like in any decent sci-fi story, many people are terrified of it, and fight it on a regular basis. The humans win the battle sometimes, destroying its intelligence and harnessing it to human managers and human rules, but the intelligence lumbers on regardless and frequently argues successfully that it should be let out of the box again, at least for a time.
I'll admit that it's possible for an AI to have more control over our lives than the economy does, but the idea of our lives being rules by something more intelligent than we are, whimsical, and whose values aren't terribly well aligned with our own is less alien to us than we think it is.
The economy is not a general intelligence.
Claim: The first human-level AIs are not likely to undergo an intelligence explosion.
1) Brains have a ton of computational power: ~86 billion neurons and trillions of connections between them. Unless there's a "shortcut" to intelligence, we won't be able to efficiently simulate a brain for a long time. http://io9.com/this-computer-took-40-minutes-to-simulate-one-second-of-1043288954 describes one of the largest computers in the world simulating 1s of brain activity in 40m (i.e. this "AI" would think 2400 times slower than you or me). The first AIs are not likely to be fast thinkers.
2) Being able to read your own source code does not mean you can self-modify. You know that you're made of DNA. You can even get your own "source code" for a few thousand dollars. No humans have successfully self-modified into an intelligence explosion; the idea seems laughable.
3) Self-improvement is not like compound interest: if an AI comes up with an idea to modify it's source code to make it smarter, that doesn't automatically mean it will have a new idea tomorrow. In fact, as it picks off low-hanging fruit, new ideas will probably be harder and harder to think of. There's no guarantee that "how smart the AI is" will keep up with "how hard it is to think of ways to make the AI smarter"; to me, it seems very unlikely.