Crouch!Moody and the Goblet of Fire -- why so complicated?

[Eddie]

No: HPFGUIDX 157249

OK, Here's something that's been bothering me for a long time.  Why
did Voldemort and Barty Crouch Jr (in the guise of Mad Eye Moody) use
such a complicated method to capture Harry?  I mean, all year they are
relying on all kinds of devices: pulling Harry's name out of the
goblet (4th out of 3), living through the challenges, being the first
to the goblet in the maze, changing the goblet into a portkey, etc,
etc, etc.  Meanwhile, Harry is sometimes alone with Crouch!Moody who
could have easily knocked Harry on the head with a wrench, thrown the
invisibility cloak over him (it's demonstrated that Crouch!Moody knows
about the cloak and can see Harry beneath it), carry the invisible
Harry off-grounds of Hogwarts, and apparate to Voldemort.

Why so complicated?

Eddie, who enjoyed the book anyway.

P.S. Similarly, if Snape is evil, he could have done the same thing to
Harry many many times.