It's going to take a lot of selling to get customers to buy into a feature that promises to look worse and take a lot more processing power at the same time. I honestly don't understand the hankering for this feature. Unless you have 200dpi displays or like to look at things reeeeally up close it doesn't buy you anything, and just makes stuff less than pixel-perfect.
It doesn't look worse, especially when the only other option is to use a non-native resolution on your display because the text on your 20" or 24" iMac or 30" ACD is too small to read.
It also doesn't take any more processing power as it's being written into the code so it executes the same way as it would as x==1. You seem to be looking at this from a young notebook users POV, and not someone with a larger display and less than ideal eyesight.
Apple could include way to alter the size of the menus and such like Windows does for the visually impaired, but they don't. You alter pretty much any text in Mail and you can use the latest WebKit builds to turn on Full Page Zoom (I did both for my mother's new 20" iMac) but there are apps like iCal and iPhoto that offer no option to make text or windows easier to see.
I set RI to x==2, and while it was great for most things, Dashboard data would increase by a factor of 2 but the windows for the Dashboard apps were still the same so it was a no go. The only option was to use a non-native app but that makes everything a little blurry.