Hey Chip-Blu-Ray is only about 30-40% off all media purchases right now, which is why the DVD is included. Most people do not buy BD's. The DVD/BD package also serves as a "value added" proposition, because families with children, or friends without BD players can lend the DVD out, or have their kids use the DVD as a 'coaster' in another room. It makes more sense for studios to 'bundle' these packages, because the entire market for 'media' is rapidly changing, given the rise of BD, existing market share of DVD, and a transition to digital downloads over the years. The 'Combos' are not going 'away' anytime soon, because it's in the studios' best interest to sell them all as a package, 'to target' all types of media consumers (1) Have moved to BD, 2)have not moved to BD, 3)are dabbling in digital downloads, etc). They also want consumers to move to BD, as by and large, there is an interest in getting them to buy hardware, and future releases on 'new release' day, so hence the combo. BD discs, 'generally' are also priced higher, though the gap has closed significantly over the last 4 years=more $$$ for studios.
Having said that studios are experimenting with multiple releases for the same movie-you see this frequently with Disney-BD only, BD/DVD, DVD only, BD/DVD/DC/3D, etc etc, and other studios have followed suit with the 'combo'...
