This is a hardware issue, not software. They should have just put the seam at the top of the unit.
Isn't apple and other smart phone manufacturers stymied by Federal Government reglaltions regarding RF signals needing to be as far away from the head as possible? That is why the antenna is on the bottom or lower right or lower left... and not at the top as you suggested.
I think that's it... the reason why... your government cares!