i think most every band, whether intentional or not, project some sort of "image"...it's hard to get signed and become well-known if there isn't some kind of image attached to the band. now some bands try harder than others to project a certain image (the entire genre of black metal for example) but comparing a band like judas priest, who helped popularize an image they created, and a band like trivium, who try to cop "underground" respectability by associating themselves with well-respected bands, is a poor comparison.
now granted, there's nothing wrong with wearing another band's t-shirt, but every pic i've ever seen of this band features every member sporting some vintage metal shirt. i just get the feeling they're trying way too hard.