I see no problem with it. In competitive benching, a bigger arch = a shorter range of motion = more weight lifted. To improve your bench you do need to bench a lot, but these stretches certainly won't hurt either.
"Generally people can't squat because they're lacking in the 'lower ab' area. As in they need to grow a set." - LtL
"No one ever got big or strong by lifting lightweights" - Carl1174
Follow my log here: Aurik's Back to Basics log
Valentin Konstantin Platz