The need to jack the aircraft, retract the U/C and then lower the aircraft was nothing to do with the Harrier. This was only needed at sea due to the restricted headroom available in the CVS hangar deck. The RAF never did it
Ships are not stable platforms and in constant motion, hence the need to lower the aircraft to the deck to change an engine as well as the height issue. Everything must be secured to the deck to prevent movement issues. Also on certain occasions, the 'goal post kit' (engine removal guidance tools) were used to facillitate the removal and installation of the ECU in poor conditions.
A RAF GR3 had an engine change down South using this method.
It certainly got interesting when the ship's bridge was asked to steer a steady course for an hour or so whilst the engine was hoisted up or lowered down and during the evolution they decided to heel the ship over and go zigzagging around the oceans.
As people who have changed out Harrier engines know, there is not a lot of room between the engine and airframe and it's more than easy to get your hands trapped.
All good fun though and a great way to annoy the fishheads below when lashing everything down or storm lashing aircraft/equipment during normal ops.