I'll agree that it's all trends and marketing. However, I'll have to disagree that many of the bikes being touted as "all around" commuters are actually useful as commuters. They can be made to work...I have a cyclocross that I use for commuting, among others...but I've never understood the reluctance of people to use bikes that are purpose built for carrying loads on a stable platform. One would think that a bike designed to carry 50 or 60 lb for years on end would appeal to people who carry more to work than I carry for a month long tour. But touring bikes are almost never suggested as a commuting platform.