Peacocking accomplishes a few things.
1. It allows you to show confidence by being a leader, not a follower of the group. Being a leader among men is crucial, just ask Double O, he is a leader. HSM people, HSM.
2. Often you'll be wearing something that a bird will feel compelled to ask you about, making you interesting. This is a good thing.
3. You can peacock to attrack certain types of girls. If you dress like Mystery, you'll attrack club chicks, like he does. If you peacock like a certain PUA I know, who dresses like James fucking Bond, you'll attract high-class women in business suits and shit, which is sexy as hell IMHO. Your peacocking is tailored to the type of woman you are seeking to attract.