What kills me is that apple doesn't offer any products in the sweet spot!
Laptops - for me, around 14" is just right. 13.3 on the MBP13 is too small, and the 15" is just too large.
iMac - why the hell do they jump from 21.5" to 27"? There are tons of 24" screens out there that would be way more affordable and are a great compromise.
Actually... that is kinda ridiculous. Size is not THAT relevant unless your eyes are really bad. It all comes down to resolution.
And NO one needs a 14" notebook that has the same resolution as a 13.3" one.
Same goes for the iMac... what resolution would a 24" iMac have? 1080p?
Alrdy got that in the 21.5". So what would you get? More real estate? No. Better image/display quality? No. It would actually be worse.
AND you'd lose space on your desk.
A different size is meaningless if it doesn't bring any new utility to the table!
You may disagree with me... but I believe this to be (part of) Apple's reasoning.