I think the size of the UI text is perfect,especially if you have auto-brightness which adjusts the brightness to your surrounding,never had an issue with the size of the UI text although I do have extremely good vision so that might be it.
I think everyone at Apple must have perfect vision -- this isn't the first time they've used too small fonts that I can't read. For instance, the font they use for the iTunes / App Store are way too small, even on the PC, and there's no way to increase font size.