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.
Fair enough.
However I'm not sure whether satoshi expected the project to be a success to begin with

Arguably the jury is still out whether Bitcoin
is a success. Sure it got nice purchasing power, but in the grand scheme of things Bitcoin is still little more than an experiment and cryptocurrencies have yet to grow up. For all we know deflationary digital currencies may be a dead end in the long term and inflation is the way to go after all.
That being said, I absolutely agree with you that the first cryptocurrency to enter the stage
had to be of limited supply. Otherwise it would have never appealed to the speculators and remained an obscure little toy for nerds and anarcho-capitalists.
I'd even argue that the abrupt supply drops (ie. halvenings) as opposed to a steady decline in issuance played a major role in generating a hype cycle; with the duration of 4 years between each supply drop hitting a sweet spot of reminding people that Bitcoin is still alive and kicking just when they had forgotten about it (ie. the perfect recipe for FOMO).
How much of it was luck or calculation is anyone's guess, but I think it's safe to say that satoshi had at least some intuition about which values to choose. Intuition is hard to put on paper though. To that extend Bitcoin might merely be an experiment to empirically verify the issuance parameters

I do believe that opting for limited supply was mostly a matter of principle though. After all Bitcoin was at least in part a response to the questionable monetary policies of the world's central banks and governments.