Not sure this is really correct. The dies of those chips not necessarily have the same amount of connections (pretty sure they are different, in fact) as the whole packaged chips has pins.
Isn't the pad limit actually a function of outline rather than area (hence maybe the reason why atom is so rectangular)?
Also, I thought the number of pads you can fit on a chip also goes up - though not as fast as transistor size goes down.
Yes, I also thought that it was about perimeter, not area...