Ultimately, the numbers were likely arbitrarily chosen. When satoshi first developed Bitcoin, there weren't prior examples to look at and see how different settings affected each coin. Nor were there enough users or miners to make it worth while to play with one setting and then another. Basically, to push Bitcoin forwRs he had to decide on values for those settings and what you're looking at is the result

I'd rally be curious, if he had to do it all over again, knowing what he knows now, what, if any, changes or adjustments would he have made? I know there is a huge contingent that thinks tha satoshi is basically anxiety, couldn't have gotten anything wrong, and therefore thinks the code and settings are perfect as-is, so such things are never discussed here, which is why I wish we could ask satoshi himself.