Janeway definitely felt as though she'd earned the rank and position.
They could've made him the Boomer (since it was wasted on Mayweather), born and raised in space, so he's got plenty of light-years under his belt and a freer/looser notion of how to get things done--so he could have a more swashbuckling charm to him (something a young Jim Kirk might've looked up at and aspired too decades later).
More focus on the growth of the friendship and his growing to trust Vulcans would've been a far better route to take their story, going from butting heads and disagreeing over how to approach situations, then on to a grudging respect before finally trusting and liking one another. Far more mileage in that rather than Archer just being horny.
A great idea that could've been explored in the 5th season, with all that's happened to him, is he still considered human and what fall out that might have for the ship/Starfleet--could've been a great way to keep Terra Prime in the background as a thorn in their side.
I LOVE Year One!!! A grander scale, jumping across several ships and locations, with a wider array of characters, exploring the beginning of the Federation would've been my pitch for the show.
Archer as a Boomer reminds me of an idea I had when I used to play around with redoing ENT. My take on it though was that Archer was a former military man who is now a Boomer. I would keep Mayweather though, and have both Boomers on the ship.
I wish they had went with a Year One type show because if they didn't want to do the Earth-Romulan War why set up a prequel series that takes place several years before that war? There's very little really that would've needed to be changed with ENT as if if they had just set the series after the founding of the Federation. They might have to change the name of the NX-01, then again, maybe not. The whole it was the Earth starship Enterprise versus the Federation starships Enterprise could still exist. Just make the NX-01 an older ship by the time of the founding, like it turned out to be anyway.