The Ben Ish Chai writes that Haman stressed that these be “brought” because he wanted a great amount of people to be involved with fetching the items, and then handed over by Achashverosh. This is because the more individuals involved in bringing something, the more honor there is inherent in it. This is why many people are involved in carrying the Olympic torch to begin those ceremonies. In Halacha, too, there is great honor in being one of the people who bring a baby boy in for his circumcision (see Rema on Shulchan Aruch Yoreh Deah 265:11). This was Haman’s plan to increase the honor he felt was due to him.