I'm pretty sure these missing patches of holo isn't intended and I think I know how this happen. Take a look at the first 5 holos in this set: Moltres, Chandelure, Articuno, Vanilluxe, and Zapdos. All five of those cards are missing holo at the bottom of them, but the only one I think that was intended not to have holo at the bottom is Vanilluxe. The next 5 holos: Luxray, Gardevoir, Lucario, Scrafty, and Cinccino seem to be missing holo in random places, except for one card, Scrafty. Now to get to my point, it seems that the first 5 holos went through the same machine using the holo pattern for Vanilluxe while the last 5 went through the same machine using the holo pattern for Scrafty. This makes sense because Scrafty and Vanilluxe are the only two holos that seem to not to be missing any holo.
Of course this is just a theory, but I think at least those 8 holos are errors.