Why would the phospholipid bilayer want to be polar on the outside and non-polar in the inside? why would it not want to be the opposite?
Phospholipids in aqueous solution under the proper conditions organize themselves into micelles and other structures - the minimum energy state. This allows the polar head groups to interact with water in the bulk solution, while the non-polar carbon chains are 'protected' from the polar environment. Water is attracted to water, and the polar head groups are attracted to water, the non-polar carbon chains are excluded.
You can get inverse micelles in non-polar solvents.
There is a misunderstanding here. The questioner mentioned "Both the interior and exterior are aqueous solutions", which is absolutely correct. However it makes evident he was thinking the non-polar part of the membrane molecules are in contact with the interior of the cell, which is wrong. The non-polar ends of the membrane molecules are entirely inside the membrane, in contact with other non-polar ends of the other layer of the lipid bilayer which forms the membrane. Both the interior and the exterior are in contact with the polar ends of the molecules.