SATOSHI has inform -> for security after one sending transactions, you can't use the same addres. and ASK yourself why?
Why? To increase privacy, it says so right in the whitepaper:
As an additional firewall, a new key pair should be used for each transaction to keep them from being linked to a common owner. Some linking is still unavoidable with multi-input transactions, which necessarily reveal that their inputs were owned by the same owner. The risk is that if the owner of a key is revealed, linking could reveal other transactions that belonged to the same owner.
While satoshi might also have been prescient about the impact of QC we're still some years away from a meaningful threat even on a nation-state actor level.