Can anyone shed light into what makes this difficult? I'd love a matte black mac, but I can't imagine this research is more than A/B testing.
It's not paint. It's build directly into the anodized finish, using nanotubes. (Kinda vaguely like what Vantablack does.) So you get a get a really deep black, not just a dark gray, and it will be very durable.
It's not exactly earth-shaking. It's just coloring a part, after all. But there's some materials science research going on, not just marketing.