Personally I'm very glad I got my Aluminum MacBook when I did. I don't want a polycarbonate case...
My guess is that machining the aluminum cases was just too expensive, it would clearly be much cheaper to simply mold a polycarbonate case. But personally I don't think they will match up from a durability perspective...
Hm? The aluminum Macbook still exists. It's just classified under the Macbook Pro line. 13", right?
Think of the polycarbonate case as Apple's attempt to make a product that's affordable as possible. I was expecting them to phase out the plastics entirely; the fact that they're keeping it and improving on it suggests that they'll be gradually lowering the price on it too.
There was an aluminum MacBook before there was a 13" MacBook Pro. Essentially the aluminum MacBook became the 13" MacBook Pro when they upgraded the specs.
My guess is that machining the aluminum cases was just too expensive, it would clearly be much cheaper to simply mold a polycarbonate case. But personally I don't think they will match up from a durability perspective...