After finishing the first season of Enterprise, I can see clearly why it’s universally regarded as the weakest series. Half the characters are totally forgettable, the time travel plot is stupid beyond belief, and the theme song is simply intolerable. Now to be fair, the reason that the Next Generation characters were so much stronger is almost certainly due to exceptionally good casting rather than to the skill of the writers — I have no doubt that Ensign Mayweather would be unforgettable if played by a young LaVar Burton, for instance — and even in TNG it took them forever to figure out what to do with everyone (in fact, the actresses who played Tasha Yar and Beverly Crusher both complained of this and were written out after the first season, and Worf is little more than decorative until midway through the series).
What stands out to me about the series as its genuine contribution is the interplay between Vulcan and human society. We’ve learned a lot about Vulcan culture and of course the interaction between the rational Spock and the impulsive Kirk is the most loved feature of the franchise as a whole. But by that point, Vulcans and humans were already equal partners in the Federation. Showing the Vulcan reaction to humans when they are still clearly the inferior and subordinate society is something unparalleled in the rest of the franchise — and it’s genuinely interesting simply in itself, apart from its role in filling in the gaps in the Star Trek mythos (something that cannot be said of the greater detail about the Borg in Voyager, for instance).
I still think it would have been more interesting to have a season or two on earth before launching the first mission, because ironically, we know far more about Klingon, Ferengi, and Borg society than we do about the actual lifestyle of the average human in the Star Trek era. The one exception is the introduction of so-called “Boomer” culture, referring to the humans who lived for years on space freighters, which became family businesses. (Sadly, though, the one representative of that culture on the crew is played by a total non-entity, so I doubt it will get much exploration.) In general, though, I’m much more fascinated by the guy in future Oklahoma who found a Klingon in his silo than by yet another mission of exploration. I’m given to believe that they finally start exploring the average human’s reaction to all this alien business at the end of season 4 — but by that point it was too late.