@darius2, you seem to have a problem understanding what A-GPS is.

A-GPS is a way, using network capabilities of your phone (or wifi) to have a clue of where you are, and then give this info to a GPS chip to get the fix quicker.

Both N810 and iPhone have a GPS chip, and they both could give you your position without A-GPS. A-GPS only comes there as a support.

The N810 has a Texas Instrument chip, which is not so good to get its first fix but is good for other things(battery life, keeping the fix,...). To make the first fix quicker, Nokia introduced, as software, A-GPS. It improved the TTFF for most of us. Same goes for the iPhone.

Now, as your question is: why didn't they put the best GPS chip (aka SirfIII) in the N810 and iPhone?
it's like asking "why didn't they put a Ferrari engine in my VolksWagen?"

And asking, us or Nokia about that is as pointless as asking VolksWagen. They made the choice they thought was the best.