Re: NGD: VM Jaguar
What’s the reason for this?
To raise to bridge. It's basically decked on these when they come from the factory. Back in the old days, Jazzmasters and Jaguars were intended to be shimmed, and usually came from Fender with factory shims installed...though not as much shim as you need these days, because the guitars also were designed to work with heavy gauge flat wound strings. Just like acoustic guitar strings, 11's were considered light, 12's were mediums, and 13's were heavies.
Raising the bridge:
1. Increases tension over the saddles
2. Gets the strings (primarily the low E) off of the vibrato screws near the rear end of the vibrato unit.
3. Gives more space underneath, which is required to use the original mute (which is not there on the Squier VMs).
4. It also gives it a more Gibson-like feel, which you might or might not like (I like it).
In addition, part of a "proper" JM/Jag setup is that you set the saddles high on the bridge plate. This gets rid of string contact on the back lip of the bridge.
All of this stuff allows the rocker bridge to operate as intended, without the strings hanging up anywhere. It also holds the saddles down a bit tighter, so they don't drift or rattle/buzz as much, and so the strings are less likely to jump the threads.