I'm not defending or attacking, but I think the idea is that: Computer UI designs in the past tried to make the user more comfortable by mimicing the textured,

I'm not defending or attacking, but I think the idea is that: Computer UI designs in the past tried to make the user more comfortable by mimicing the textured, three dimensional environment that humans exist in. Look around; every object you interact with outside the computer is shadowy, rounded, bevelled and textured. The current thinking is that computer UI should not need those real-world cues in order for users to feel at home in the digital environment. See also; skeuomorphism