Design means different things to different people. I wholeheartedly endorse Steve Jobs’ philosophy:
Most people make the mistake of thinking design is what it looks like. People think it’s this veneer — that the designers are handed this box and told, “Make it look good!” That’s not what we think design is. It’s not just what it looks like and feels like. Design is how it works.
Design isn’t the outer skin of the product. It’s not the Photoshop layer effects, the trendy noise and linen textures, or WebKit CSS image masks. Those things are tactical tools that can be used to stylize a product, but design is a holistic concept that defines how the product works.
I don’t think it’s controversial these days to state that successful product development must begin with design first. The way the product looks, feels, and behaves is the product as far as the user is concerned. Defining these things is the role of the designer. Bringing them to life is (usually) the role of the engineer.