Look at the set of rules like a gentlemans agreement. Kicking a guy in the testicles is very effective, but it's not a very "manly" thing to do. Trust me, I do it all the time in street fights.
What a lot of older fighters did was take the other guy down and repeatedly headbutt him and you know what, it works. But it also causes brain damage.
Other traditional martial arts techniques are allowed, they're just not really effective when you have to worry about a guy taking you down and submitting you. Let's say groin kicks were allowed, I would have to have my hands below my waists at all times. That would defeat the purpose of boxing so there really wouldn't be much of a fight. It would literly be human cockfighting.
But I do agree with you it does cater more towards wrestling. Because look if I can hold this guy down for 15 minutes, I get the winning purse. I could give a shit about what the fans think. But then again he had his opportunity to knock me out.
If you are very interested in getting into the sport and murdering people, you could elbow all you want when he takes you down to the ground anyway so yeah..