Another good point is that remixes like this are origional because, like the origional songs they are based off of, no one else has made them before and they were created completely out of someones hard workl and imagination. It's that persons own peice of work, like Maddie said in her blog post, "no one is ever going to make a remix EXACTLY like this"(Hauser), it is the remix artists origional peice of work.
It's like a whole new method of creativity. You are using others work to help produce your own. I think Alyssa describes this process best in her blog when she says that, "what you are doing is taking a bunch of different elements and putting them together in a skillful way, making your own artistic choices to create something new that has never been done in that exact way before" (Policarpio). So basicaly, instead of creating something out of nothing, you are creating something totaly new out of something already made, which is still very creative and original.
Car companies do this all the time. Many companies have "mashed up" their vehicle models with other models from a different manufacturer to create their new model for the next model year. This is evident in multiple ways.
First is technology. One company is almost always the first company to come up with some nifty trick, like say back in the day it was seat belts or power locks. And then, other companies are soon to follow suit, keeping their origional designs and mechanics, but incorporating this other manufacturers new gizmo.
The other thing is the the actual mechanics of a car. Many companies have mashed up their cars with another manufacturers engine or transmissions, and made new models or their car that is still their car but it is just incorporating, or mashing up, features from another manufacturer. Chrysler, for example, used to put Mitsubishi engines in all of their small engine cars. They were still Chrysler cars and in no way Mitsubishi's, but they just incorporated their technology and incorporated it differently to fit in their cars, which also takes creativity and ingenuity like mixing up songs.
My point with this analogy is that mash-ups don't only happen in music, it's just that that's where its mostly criticized, but the idea of mashing things up happens in almost every industry. One company takes ideas from another on new ways of doing things. It's basically the same concept. So, if this technique is used so much in so many ways, and the products of "mashing things up" are unique, then I believe mash-ups and remixes are totally unique, and take just as much creativity and effort as original works.