The problem was, Scott had to have good writing in order to shine as Archer and couldn't rise above when he didn't get it. The same writers who wrote Archer also wrote Trip and Phloxx (and everyone else). But we saw Trinneer and Billingsley defeat bad characterizations with their natural, relaxed, and charismatic performances.
Neither Trip nor Phlox were mouthpieces the way that Archer was. They only needed to attend to their work and express their quirks. Archer was designed to be more than that, expressing the ambitions of humanity as well as the ideals that would emerge in TOS and the 24th century series.