Ask HN: Why did EULAs for purchaseable, installable software become the norm?

I understand that web services need Terms of Service in order to regulate what goes on "under their own roof". However, why did EULAs become a thing for boxed, purchaseable software that was able to just be installed on the owner's PC?

As far as I understand it, copyright law already had everything these publishers needed in order to stop piracy. For example, why even have a clause for disallowing reverse engineering, if redistributing a cracked version already counts as a "derivative work", and thus copyright infringment?