It isn't deliberately unself-conscious or deliberately formulaic or deliberately anything, as far as I can tell. It isn't like watching Smallville where the plot is entirely haphazard but you still feel that the writers take themselves very, very seriously. Lois & Clark isn't even deliberately non-serious. It's all very Zen-like.
It is helped by the fact that Dean Cain is not a great actor and Terry Hatcher is little better. John Shea is better than them both but after about ten minutes in the pilot, Shea obviously decided to go for over the top villainy. He has that voice (sort of deep and rumbly) that gives anything he says extra cache, and he uses it.
One of the main reasons I think the show works is that Dean Cain and Terry Hatcher are good-looking people (they make, as the saying goes, "a striking couple") but not so devastatingly gorgeous that you never buy into the premise that these people can have normal lives and relate normally to the people around them. Of course, the whole Clark not looking like Superman thing is silly. But the writers know that. Of course it's silly! Ha ha! So suspend your disbelief already! (There's a scene in the pilot where Clark removes his glasses and says something like, "People won't know who I am. See--" and his parents kind of make these, "Uh huh, whatever honey" replies.) We are having fun, the writers seem to be saying, so much fun we don't care whether you (the audience) are having fun or not. This type of writing approach is rather refreshing.
The other thing I like about the show is that unlike the Superman movies (at least, the first one, which I rewatched recently) Clark IS Clark. In the Superman movies, Superman is Superman with a Clark disguise. But Clark of Lois & Clark is intrinsically Clark--he just happens to have powers and so adopts a Superman disguise. It may sound like nitpicking, but it actually makes a huge difference. In the Superman movies, Superman woos Lois as Superman, but Clark of Lois & Clark woos (and becomes good friends with) Lois as Clark. In fact, sometimes, I think the writers forget that the show is, eh hem, about Superman, not about this particular reporting team. Oh, yes, they seem to say, uh, throw in a Superman scene here.
And the show can be downright hilarious, usually in a comments-in-passing kind of way: a character says something, and you go, "Wait, huh?" There's this scene where Lex Luther marches around a room where he has all these artistic artifacts: the missing arms of Venus, the Boy in Yellow. The script doesn't even stress it. He just mentions the artifacts and goes on, and you're sitting there going, "What? What? Did he just say what I think he said?" (In that same episode Shea and his butler are discussing Superman's globe: "It's better than cable," one of them says. "In the future, every household will have one.")
What makes it so bizarre is that unlike Buffy and Angel, the humor--like everything else--doesn't seem to be deliberate. Nobody seems to be using humor as commentary or to create a certain type of show. It's just . . . there, available, okey-dokey, let's use it!
Which, all in all, makes the show extremely relaxing to watch.