Edited by Fred A on January 4, 2015, 2:58 pm
Here's my two cents (trying not to be opinionated but factual):
Back in the 80s when the first bench shirt was introduced by John Inzer (this was even before his blast shirt) it was designed for protection. We realized about a 4% to 5% increase in the bench. However, the grove didn't change from raw nor did the training. Example: no one was doing board presses.
Today's bench shirts require a new grove, specialized training and a depth of knowledge on how to utilize the shirt to the greatest advantage. The advantage a lifter realizes is from 25% to 45% (realistically). This isn't good or bad. It is what it is. Two different applications of the same movement. Now why the move toward raw?
Today's athletes entering into powerlifting are crossover athletes. They compete in powerlifting, crossfit, physique contests, endurance stuff (tuff mudders) and local hybrid strongman meets. The expense and specialized training steers the new athlete away from equipped lifting. Contrast that with the powerlifters of the 80s, 90s and the first decade of the 21st century - those lifters just powerlifted. It was the anomaly that someone crossed-over. And with the exception of Roger Estep, we were all too fat to body build anyway.
It really doesn't make one better than the other...simply different. Simply the facts.
Now my opinion - if you can't lift it raw you can't lift it.