Why does samsung have a love affair with plastic?

Seriously, i mean look at there laptops the series 9, series 7 chronos there all made out of aluminum, so why can't they use the same materials on there phones, look at Htc sure they used have a poly carbonate affair but with the "one" they used something different. It's not that i hate plastic, it just that it degrades the value of the device on hand. in school people call samsung samshit just cause there products look like a low cost china phone.