So is there a big advantage going with the rMBP if you're only going to be using it at the 1440x800 resolution?
People really seem to be missing the point on this. If your computer used 2880x1800 resolution everything would be really small and unusable. But that doesn't mean the new display is useless.
I have two laptops sitting next to each other. One is a Dell XPS M1530 at 1440x900 and the other is my new Retina Macbook Pro scaled to 1440x900. The Retina display is far better because it's got so many more pixels and when I go back to my Dell it looks like crap.
The same thing happened with the iPad. When they came out with the Retina dispaly everything didnt' get smaller... everything got clearer.
Some people are complaining about apps being blurry but I'm running Google Canary and it's fine and for the apps that haven't been updated yet they will be so I'm fine with that.