Is designing and producing a dirt cheap charger really that hard?
The two main areas that I can forsee are the contacts and the power.

Yes, spring-loaded contacts will be essential.  And yes, that means a stronger pack.  And that means more cost to the manufacturer.  At the moment the cardboard and plastic blister-pack style of packaging is a fraction of the overall cost of the product.  To replace that with something able to withstand the contact springiness would increase its cost many times over.  It would be hard to make it economically viable as a pack of batteries any more.  As a disposable charger the costs would probably out weigh the benefits.

Secondly, the power.  Modern mobile phones use quite a large amount of power.  It is unlikely that a pack of 4 AA batteries will be able to charge a phone to its full capacity - in fact you will be lucky to get 50% capacity.

In a dire emergency, yes, this could be of use, but there are already products out there that allow you to charge your phone from external batteries, such as the Thumbs Up Emergency Charger and similar.  There are also solar powered ones which have an integral battery.  Just leave it in the sun and you have the emergency charge at your finger tips.  Much greener (and cheaper in the long run) than 4 disposable AA batteries each time you want to charge.