I know from watching this project mature that the case has gone through a couple of changes. I know that the plastic used is also twice the thickness of a normal USB drive.
However, I am not able to see why aluminum was not used. The isostick IS very cool. Why not make it look very cool?
Personally, I hate anything that feels plastic-y. I will pay more and go out of my way to buy flash drives with a nice metal/aluminum finish. Its just kick ass, and the quality of construction just feels so much more solid and durable.
Just my $0.02. You have an awesome product, why not make it look and feel like it?