Is aluminum really a better build material?

This is something I truly don't understand. Why does an aluminum shell intrinsically make a phone "better designed"? Aluminum scratches more easily, is harder to modify and paint, and takes shock worst than plastic or Kevlar. To me, it's almost as stupid as the iPhone 4/4s being praised for design considering the front and back glass (this coming from a Nexus 4 owner. Seriously dumb mistake, no matter who does it).