- The double-click isn't ideal but way less prone to accidentally triggering the slow, painful operation of opening files and programs on ancient floppy disks and CPUs.
- Cutting and pasting ideally should consistently work exactly like that operation in real life; randomly changing what you've tried to move over and dropping information would be surprising and confusing.
Anyway, "almost all" doesn't mean "all". The number of correct decisions Apple made back then is astonishing and vastly outnumbers the mistakes. Fire up an emulation of the original Macintosh sometime and it feels surprisingly modern and intuitive - far moreso than its contemporaries (Windows 1.0, AmigaOS...)