In defence to Michael he is correct
Taken from
http://www.safecomputingtips.com/laptop-ergonomics-tips.html
"9. Avoid resting your wrists while typing. Keep your wrists as flat as possible. Use whole hand and arm movements to navigate the Laptop Ergonomics keyboard. Avoid bending your neck and head forward to see the screen. This is the way to arrange your seating posture to avoid Ergonomic Laptop disorders."
I can understand that resting your wrist on that area hurts, but even if it were rounded off
#1 the design would look funny from a side profile view.
#2 Components would have to be smaller as the fillet in the aluminum would need support as to not deform under pressure.
and lastly and most important.
#3 "Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist." resting your wrist on that area wether sharp or rounded WILL CAUSE CARPEL TUNNEL. In fact one reason why I like that it is sharp is that it keeps my wrists off it. Must like a stove is hot so you won't touch it.
I hope you can easily correct your habits. In fact Michaels suggestion is a great easy fix form most people. But if you insist doing work on your lap they make pads/stands for that.
FYI Apple does not recommend the use of their notebook computers on laps, for several reasons. Air flow is restricted and people tend to use bad ergonomics. Apple recommends the use of their notebook computers on a flat surface like a table or desk.
http://www.apple.com/support/macbookpro/care/
"General Safety Instructions
Read and follow all instructions marked on the product and in the manual before operating your MacBook Pro. Be sure to keep the instructions handy for your reference and for others.
Set your MacBook Pro on a stable work surface.
Keep your computer away from sources of liquids, such as drinks, sinks, bathtubs, shower stalls, and so on.
Protect your computer from dampness or wet weather, such as rain, snow, and fog.
The MacBook Pro power adapter port contains a magnet. Do not place magnetically sensitive material or devices within 1 inch (25 mm) of this port.
Never push objects of any kind into the MacBook Pro ventilation openings."