I wouldn't devalue graphic design as the parent did. There's room for a lot of improvement in the graphic design — what's often derisively called "just the way it looks" — of most digital products. Graphic/visual designers were somewhat restrained by low resolutions and slow GPUs. Evolving display technology will give rise to better graphic design both in the web and other digital products.
Good interface designers should definitely know the basics of the technologies used to implement their creations, in the same way industrial designers are expected to have some understanding of materials and manufacturing processes. It's often said that designers thrive on constraints: a designer does his best work when he knows the limitations of his tools, and works with their limitations and defects to create something useful instead of pursuing some impossible level of perfection. Designers, too, have to ship, and they ship best when they know what's behind the facade.
Good interface designers should definitely know the basics of the technologies used to implement their creations, in the same way industrial designers are expected to have some understanding of materials and manufacturing processes. It's often said that designers thrive on constraints: a designer does his best work when he knows the limitations of his tools, and works with their limitations and defects to create something useful instead of pursuing some impossible level of perfection. Designers, too, have to ship, and they ship best when they know what's behind the facade.