First off -- Why I think JQuery is misused

JQuery is a JavaScript library, which has been coded with JavaScript to make it simpler to develop applications with cross-browser support for commonly used JavaScript functions. However, with the improvements made in cross-browser JavaScript support and functions, JQuery is becoming increasingly unnecessary. I think it's absolutely ridiculous when I see people using JQuery for small projects, literally quadrupling the amount of work to be done by the browser just so that the person coding doesn't have to type in "document.getElementById" a half-dozen times. The only time you should really use JQuery is if the time saved is actually more important than the quality of the end product, which I don't think should ever be the case.

And secondly -- My interesting idea for extra security

I've been programming a Chrome extension for securely managing (using crypto) login data and cookie sessions for multiple users locally. What I'm looking to protect is the logged in user's "Master Random Password" (MRPW) value, which is a global variable and is used for encrypting and decrypting purposes while the user is logged in. Specifically, I want to protect this value from being extracted from XSS-like attacks or even from a person with direct access to the JavaScript console window. What I came up with is a very simple proof of concept, the concept being that I can create a JavaScript variable and protect it from being read, override that variable, and use it for calculations (such as encryption/decryption).

Code:
var LiUMRPW = {};
function SecureMRPWInit() {
	var SecureMRPW = "";
	LiUMRPW.Set = function(NewUserMRPW) { SecureMRPW = NewUserMRPW; }
	LiUMRPW.Get = function() { return SecureMRPW; } // Proof of concept, and only way of retrieving MRPW once it has been set
	} SecureMRPWInit();
Thoughts?