They did make them, plenty of them and some quite bad, but not as bad as original LiS which was a kid's show. And I'm leaving it at that.
You're hung up on the "kid's show" thing as if it were somehow unique, but on this point too, you're mistaking the norm for the exception. I have to assume you're significantly younger than I am, because up until the mid-'80s or so, the
default was for science fiction TV shows to be kids' shows, or at least assumed to be such.
Star Trek was the only 1960s non-anthology science fiction show that
wasn't aimed at children, and even it was mistaken for a kids' show for decades, dismissed as such by critics, and routinely syndicated in daytime/afternoon time slots. '70s stuff like the bionic shows,
Wonder Woman, Galactica, and
Buck Rogers was all made to be kid-friendly (even
The Incredible Hulk was to an extent, in terms of its toned-down violence, even though it was written on the level of a smart adult drama). Early '80s stuff like
Knight Rider? Definitely juvenile. It was only later in the '80s that we started to see more adult-skewing stuff like the
Twilight Zone revival,
Max Headroom, TNG, and
Quantum Leap. So it's only people who've grown up in the '80s or later who would see SF shows for kids as the exception to the rule.
You're also making an assumption that always disturbs me: That being for children implicitly equates with being low in quality. What a horrifying way of thinking. Surely making something for children carries a responsibility to make it with as much quality and care as possible. The best of children's television is more than good enough and smart enough for adults to enjoy too -- see
Batman: The Animated Series, Gargoyles, Avatar: The Last Airbender, etc.
Also, in an ideal world, surely SF shows made for children would try harder to have good science, for the sake of being educational. It doesn't make any sense to say that adult shows should be expected to have better science than kids' shows, since kids are the ones who could benefit the most from learning good science. But the truth is, there's never been a correlation between age range and scientific plausibility in SFTV or movies. The most adult-skewing shows usually have just as much nonsensical science as the kids' shows.
This is all your opinion.
No, as I said, it's a
deduction. I've presented you with the chain of logic that led to the conclusion I offered.