All these "commuter" bikes are labelled thus under a set of very restrictive assumptions, such as that a commute can only be short(ish), flatt(ish), and that the commuter will prefer to ride in an upright position wearing his work clothes while having a ton of stuff in the panniers. There are a helluva lot of commutes out there that don't fit that description. There are commutes that involve riding on beat-up dirt roads and would be best served by an MTB; there are commutes that span dozens and dozens of miles and involve brutal climbs - gotta be a masochist to attempt it on an Electra Townie (every day!). There are commuters who hate panniers and prefer to wear a backpack or a messenger bag, and there are commuters who don't even need to carry anything that won't fit into their pockets. Some commuters can keep their bikes in their offices, so they use their $5 K babies to commute and train at the same time. Others have to lock the bike outside in an area famous for an abundance professional bike thieves and thus will never ride anything more expensive than a dependable beater. Suggesting that all commuters can be served by one particular style of bike is just silly. I bet you most people on this forum do not use that kind of bike to commute to work, and it's definitely not due to ignorance.

Edit: As I see, someone's already covered this. Well, great minds think alike.