I commute with a messenger bag too (timbuk2 too!). It's just convenient to be able to go to the store on the way home, or to multiple locations. It carries enough, but it's true that on the days I have to lug around my laptop, I'm not to happy about it. It's both function and style, I think. I like how it hangs lower on the back, so I don't get that sticky sweaty upper back. I can easily reach into my bag to get stuff out without having to swing it around, and it closes securely with the large velcro tabs even without using the clips. If you get a messenger bag, make sure it has the cross strap to secure the bag properly while riding. And I'd recommend a brief case style handle. I don't have one, and that's the one thing I wish I ordered on my bag.