I take it satoshi did not imagine this would happen with 1mb block size.
Yes. He did. He discussed it multiple times. Why do you think he didn't?
If we are to bring this main stream why not just increase block size to 500mb or at the rate of visa at 21k transaction per second.
If you think you can get people to use your fork, you are welcome to do so. Bitcoin is open source and decentralized. Anyone can change anything they want. The tricky part is getting enough people to use your software to make the effort worthwhile.
Is this too simplistic?
Software changes always have side effects. They are not always predictable. Have you considered all the possible side effects of blocks that big? Are you certain that 500MB is the "right size"? Perhaps that is much bigger than necessary? Perhaps that isn't nearly big enough? What analysis have you done to determine that 500MB is the right size for a Bitcoin block? Did you just pick the number because you thought it "sounded big, but didn't sound too big" in your mind?