those are 100% not obliques. they are serratus anteriors.
if you want to work your serratus anteriors, try doing some stiuff armed push ups. in other words, lock your arms in a push up position, and just move up and down at the shoulder joint.
popping the shoulder is a big part of snapping your punch. guys who have somewhat non-threatening standup also often have very strong, tight, and bound-up shoulders, such as wrestlers like couture or ortiz. the kind of shoulder strength and integrity needed in wrestling is actually somewhat antithetical to striking since in wrestling there is a lot of emphasis on isometric holding with the upper body. you have to protract your shoulder girdle hard to snap a punch correctly, and that required both shoulder strength but also fluidity of the shoulder girdle and flexibility.
here is an example. notice how floyd's shoulder drifts forward during the punch.
bench press is probably not a good exercise to increase punching power, because in the bench press, you tend to retract your shoulder blades (draw themback and together tightly) in order to shorten the range of the lift and decrease the load on your rotator cuff muscles. this often leads to a shortening and inflexibility in the supraspinatus, a rotator cuff muscle. this leads to a lack of shoulder mobility. if you bench heavy without drawing your shoulder blades back, you stand a good chance of developing a chronic shoulder injury.
try some stiff/armed pushups or lie on your back and move your shoulders forward and back with dumbells.
of course, the prominence/definition of a muscle has little to do with its strength or performance. if you get lean enough, anyone's serratus anteriors will show.