I agree that a lot of what we do in cycling seems to be a fad, but I don't think that 100 PSI, pencil-thin tires were ever a good idea on real-life roads. (A velodrome is a different story.) IMHO, the pencil thin tires of the past were the result of "it seems like a good idea for going faster" without actually doing the research.

Up until recently, road bike tire size was limited to a 700x25C (approximately) due to the brake caliper limiting that size. Now that disc brakes are the norm, rims have gotten wider and so have tires... and I'm thankful for it! In the last Tour de France, 700x28C was a common tire size and 700x30C and 700x32C was common on the Paris Roubaix. Where I live in lumpy-road Wisconsin, having wider tires has radically reduced the amount of fatigue on my body, allowing me to ride further w/o feeling like my bike just beat-me-up.

That being said, you don't have to wait for marketers to tell you which tire size is faster... Try different sizes and find out for yourself what works best for you. I've ridden tires from 19C to 35C in width (mostly for light gravel) and for me, 700x32C is a sweet spot between comfort, performance, and handling.