Man, you know what analogy I've never heard? The one where some poster says using a Speck/Incase case is like wrapping your couch in plastic. Except for the part where you don't carry couches around with you all day. Or the part where some people like to personalize a little. Or the part where no one should care what someone else does with their couch, laptop, or lamborghini.
Anyway. I don't normally use one of these, but I own the speck satin in purple because I got one super cheap. I've been using it lately because I've been on the go a lot. They're also useful when I'm flying, as airport conveyor belts and such can be rough.