It's an unfortunate situation at Erin Hills. The course was designed to play firmer and with wind. So, two of the primary defenses of the course are absent and considering that, it's holding up ok.
The US Open is a brand built on tough, parkland golf. It should slim down the rotation and get back to what it is.
As for who had the better round, the five best scores in the top ten today were, 63, 65, 67, 68, 68 on a par 72. In '73 it was 63, 65, 68, 70,70 on a par 71. That would indicate Miller's round was better, although he shouldn't be the one pointing it out.