That's what he did, what I argue is that you cannot leave it to completely arbitrary numbers and expect the project to be a success. I doubt satoshi punched the keyboard and whatever numbers were typed that's what he used for total supply, block rewards and whatnot.
If for instance he decided to set the thing similar to Freicoin, which was inflationary and introduced the idea of "digital demurring", Bitcoin would have never caught up as a store of value, which coupled with the blocksize limitation, it would have been a failure. In fact, I suspect satoshi knew 1MB blocksize was set in stone years before it even was brought up by anyone else. The way I see it is that those things are "hard coded" in practice, but not mentioned in a explicit way. He was aware on the game theory that would unfold.
you have to remember that bitcoin has always been an experiment and practically the first of its kind. so you can't expect everything in it to be absolutely perfect. Satoshi considered a lot of things including the supply and i'd say 21 million was a good decision.
as for block size i don't think he had any plans from the beginning. the initial limitation had nothing to do with block size but it was with the database (implementation limitation) and then the actual limit was placed in 2010 to prevent spam