Instead of wanting to be convinced by the research, I'd suggest implementing the advice into your own training for six weeks and seeing what happens.
Brad Schoenfeld wrote Light Weights for Big Gains a few years ago, looking at the same study and others. Chad Waterbury has written about the benefits of high rep training (though not really to true muscular failure). Plenty of other coaches and, like, pro bodybuilders have spoken about the benefits of working in all rep ranges - low, moderate, and high. It's out of style, recently, but it works.
Not really. And Thib was very clear in the article that going that light most likely isn't necessary or efficient for health, experienced lifters. 30%RM is probably close to 50 reps per set. While it may be useful as an occasional finisher or something similar, training just in that range isn't going to be a great bodybuilding plan for any extended period of time.
I will say, though, Watertbury's SOB Training program (which he wrote long before this study was out) has days training with 30-50 reps, and days training 2-6 reps, and days training inbetween. And it's one of my favorite routines around. Brutally simple, felt great during and after, good stuff.