Well, DVD inherited special features from the laserdisc format. For years before DVD even came on the scene, optical disc formats very often utilized special features as an added bonus. The Criterion Collection was the first home video distributor to do this, and it wasn't to "entice the viewer to upgrade," it was to provide a "film school in a box" for the consumer. There's plenty of blurays that are packed with special features - Jaws was stocked to the gills, all of Ridley Scott's movies get gigantic packages of features, and Criterion still loads their releases whenever possible. It depends on how "big" the release is.