This kind of illustrates the point I've been making. Lets assume for the sake of this discussion that what you write above really is an accurate description of the Trip character. Connor Trinneer took this bare bones, simple character and using his natural charisma and other acting skills turned Trip into THE most popular and respected character on the show.
Scott, working with Archer, a character who by your assessment, is much more complex, succeeded in making him into one of the least respected and least liked Trek captain characters in all of Trek.
Unlike Trinneer (and Billinglea), who was handed a pile of sticks and used them to build a mansion, Scott was handed a similar pile of sticks and built a "stick" figure home which lacked depth and any symblance of mystery, or complexity.
Considering your description of Trip and what Trinneer did with the character, maybe Connor should have played Archer.
I think it's the responsibility of the writers to write for the actors they have. They knew what they had, and Scott in his element is very good I think.
Like I said in my post earlier, Scott doesn't play mad or angry very well. So I think if you want them to excel you write to their strengths.
Having a character that lacked the complex backstory and purpose of Archer did not put Trinneer into a disadventageous situation. It helps an actor to have the room to put their own input into the character, to actually contribute to the process of characterization, as well as to let the character grow organically as stories evolve. That's not to say that Trip was uninteresting, but he had space to evolve and be himself. Too much was predetermined about Archer, and worse, he never was allowed to just be himself. He had to represent 100 years of disappointments that were not his own.
Now, we've seen Bakula succeed in a roll in which he had much more leeway. On Quantum Leap, his character was forced to adapt to new situations and new personalities. He kept his moral core, but Beckett was never completely himself. That situation is much more analogous to Trip than to Archer. On the other hand, I've never seen Trinneer take on a roll as complex as Archer.
Like Yanks writes, there are some things that Bakula doesn't do well. Archer was indignant a lot of the time. Bakula doesn't do self-centered very well--no one will mistaken him with Tom Cruise--so often he appeared petty. However, it also made no sense that this would be the constant attitude of the character. It took two and a half seasons for the writers to realize that he needs to go with the flow more? Moreover, he was often required to represent values that were yet to take shape. The core of his being was to help the Valakians: he should have opposed Phlox more directly. He shouldn't have been prefiguring the Prime Directive. Little things like that would have given Archer more of his own personality rather than being a symbolic representation of the Star Trek future.