Well, I mean, the guy's fist is the size of a fucking ham, so it kinda makes sense to me to that his punch would be more effective than others, to be honest. But yeah, they overdo it.
What bothers me more is the fact that closed fists are supposed to be illegal. Obviously they break that imaginary rule all the time, but every once in a while they spotlight it, and you often see the referees signaling that a strike was open-handed, so they do try to pretend that the rule is legit. Until Big Show does it. Then for some odd reason they blatantly refer to it as a punch and nobody has any problem with it. Continuity errors like that bug me.