Why is 1440 x 900 "Best" for the Retina Screen per Apple?

Question

Okay, in the System Preferences folder you can set the new MBP-R screen to one of the following settings with the description Apple provides by going to the System Preferences folder, then choosing "Displays", then unselecting the default "Best for Retina display" button by choosing instead the, "scaled" button.  When you do that, you get the following choices with warnings on four of the five choices (for a screen shot see the link below):
1024 x 640,  Larger Text, "Using a scaled resolution may effect performance."
1280 x 800, "Using a scaled resolution may effect performance."
1440 x 900, Best (Retina)
1680 x 1050 "Using a scaled resolution may effect performance."
1920 x 1200. More space, "Using a scaled resolution may effect performance."
There is no option for native 2880 x 1800 as presumably the text would be so tiny.
My question is, why does Apple call the 1440 x 900, "Best (Retina)"?  What is best about it, why do only the other four have the scaled resolution warning since they all five are scaled are they not?  Peformance concerns aside, can't I have confidence that all resolutions will be crisp as all are scaled as none are actually native (2880 x 1880)?
Then, Anand Tech has an article on how Apple handles this scaling, and they say,
"Retina MBP ships in a pixel doubled configuration. You get the effective desktop resolution of the standard 15-inch MacBook Pro's 1440 x 900 panel, but with four physical pixels driving every single pixel represented on the screen. This configuration is the best looking, . . ." 
And they note the other resolutions have the potential to suffer performance and picture quality loss compared to the "Best" setting in the middle.  But they just say this quality drop "can" happen, not that it "will" happen.
http://www.anandtech.com/show/5996/how-the-retina-display-macbook-pro-handles-sc aling
Can someone explain why this middle setting is inherently "Best", is it because the native resolution is divisible by this setting (2880 divisible by 1440; and 1800 divisible by 900)?  And why does Anand Tech say there might be a quality impact in the other four?  When would quality be compromised, when wouldn't it?
Thanks!

Answer 1

GTCA wrote:
Can someone explain why this middle setting is inherently "Best", is it because the native resolution is divisible by this setting (2880 divisible by 1440; and 1800 divisible by 900)?  And why does Anand Tech say there might be a quality impact in the other four?  When would quality be compromised, when wouldn't it?
Thanks!
Basically the native resolution of the retina display is 2880x1800.
so if you're using 1440x900 then everything is perfect (which is why apple recommends it). Every pixel can be mapped to 2 pixels of the retina display, and everything is sharp.
for other resolutions,
Every single (clear) pixel, gets blurred with it's neighbors, or displaced and doubled, changing the size and shape of the displayed images.
Imagine two grids. One is 2x2 (4 pixels total). The other is 3x3.
Now if you scale up the 2x2 to the 3x3, you'd think you'd be ok, because the 3x3 is bigger, but what do you do with the middle pixel? Which corner's color does it get?
if you choose any of the 4 original pixels, you distort the image, so the only choice is a blurred mix of all 4 colors. It's a mess.
This is what happens when apple tries to display a 1920x1200 resolution desktop on a 2880x1800 resolution screen.
It *****.
As a photographer all I can say is...
no thanks.
I'm waiting for a 17" macbook pro with a decent native resolution, or it's time for another brand of computer.