Colour differentiation and more UI texture makes it more usable and obvious what you can "do" in the mobile skin
Depending on the colour choices, colour differentiation can be perhaps the worst choice in any UI. Depending on which research you read, anywhere from 10% to 50% of all males have some degree of colour deficiency. Almost all UI designers have perfect or near perfect colour vision, so they really have no idea how to deal with such a large demographic.