With the ship design (and even with the character outlines) Berman and Braga really did restore the feeling that space exploration is dangerous. As intriguing as NX-01 was, I wouldn't want to be on it or near it. And every time Archer said, "polarize the hull plating," I thought, "fuck no! raise the shields! raise the shields!" Consequently, Enterprise's comparatively modest explorations still appeared risky.
Not only did the ship and characters support the notion that space exploration would be dangerous, but also that it was an exercise in making things up as you go. However, that did not mean freedom so much as missteps and consequences. I hate that Dear Doctor and Cogenitor pre-figured the prime directive so clearly, but it made sense that their faith in their altruism (as much as their faith in their technology) would be tested. And by the end of the series, the future would come down to a battle between competing visions of humanity, one that was human-centric, one that was humanitarian.
The bigger problem was not whether Enterprise, as a series, successfully represented the texture and atmosphere of early deep space exploration (which I argue it does), but whether we find it charming. Some of that came down to execution. Archer had a chip on his shoulder, but Bakula couldn't dial in closer than Archer being outraged. On the other hand, Bakula represented the discontents of exploration quite well. However, I am starting to think that the timing of Enterprise was really poor. It seems strange that, as has become often commented on in the last year, that there has been a resurgence of interest in Enterprise. Obviously, the HD and Netflix releases of the series has helped. Nonetheless, there is a current Star Trek franchise that fans can fixate on. I am starting to think that the mid-2000s wasn't as interested in exploring the past as the 2010s are. Enterprise was obviously set in the future, but it was always conceptualized as a history of previous ST series. With the temporal Cold War, the 22nd century was not in control of its own destiny: it was a function of actions taking place up to and including the 31st century. Quite possibly, audiences weren't as interested in exploring their own history to see where their actions might lead. The mentality of the era didn't really support reflection as much as action. If the Xindi arc was comment on the War on Terror, there was much more second-guessing in the former than in the latter.