Fashion is a science, or at least it is governed by human behavior in their sense of time. "Freshness" provides a feeling of improvement over time, while "staleness", though more familiar and comfortable, provides a sense stagnation, that time is frozen. It is really no wonder why young people are interested in being "fashionable" (they want time to progress, they want change) while old people are often not so interested in it (they already have a lifetime of change to reflect on).

For many websites, sure, it is superfluous, but the psychological effects are massive; ignore it at your own peril.