At the same price point?
If Apple installed a better screen that cost more, they would pass that cost on to the consumer, and then you'd be whining about how the MacBook cost too much.
It's a compromise. Which generates less whining - a sub-par display, or too high a price? Most people outside of Mac forums have no clue about the quality of the display, so it's an obvious choice...
If Apple made a MacBook with a better screen, more connectivity, etc. etc. etc., it would cost $2000 and be called a MacBook Pro.
(And yes, for the record, I would love to see a 13.3" MacBook Pro with a better screen, Firewire, discrete graphics, etc...)