Lee stated that the reason why they went with the plastic body is because Samsung wanted to strike a balance between manufacturing efficiency and the demand for a “premium” product. Instead of focusing merely on the aesthetics of the device, Lee revealed that Samsung wanted to account for everything, such as how the choice of materials could possibly affect the manufacturing process. This is actually a pretty good strategy because if you might recall, back in 2012 there were reports that the iPhone 5 was facing some production difficulties due to the aluminum unibody.
However with more manufacturers starting to leave plastic behind, like Sony with the Xperia Z and HTC with the HTC One, it is odd that Samsung has decidedly stuck to their guns. The South Korean company has argued in the past that plastic components are more durable in terms of absorbing shocks when dropped, but this has not stopped their detractors from claiming that their products feel “cheap” despite sporting some impressive hardware under the hood.
In any case Lee believes that Galaxy S4 will have “a nice balance between [manufacturing efficiency and premium fee] this”, but we guess we will have to wait until the 14th of March to see for ourselves.