There's nothing wrong with it, but I do think the 'kiddy' mindset probably prevented studios from taking a chance and putting some real effort into unproven characters, especially if they would be at all expensive to film. There is a reason the superhero boom happened around the same time that studios and audiences started taking superheroes a little more seriously.
And see, that's just the attitude that shocks and disturbs me -- that if something is for children, there doesn't need to be any effort or care put into its quality. I mean, think about that. It's depraved! What kind of sick, twisted society doesn't care about the quality of the things we do for our children??? Surely our children deserve nothing less than the absolute
best effort and quality we're capable of giving them. The idea that adults should hog all the good stuff to themselves and just toss inferior scraps to their kids is horrifying. How can any adult with a shred of decency or responsibility imagine that's okay?
And, heck, some of the best SF/fantasy/superhero fiction out there in the past few decades has been made for children, but made with the quality and intelligence that children's programming rightly deserves -- things like
Batman: The Animated Series, Gargoyles, Avatar: The Last Airbender, The Legend of Korra, How to Train Your Dragon, books like the Harry Potter series, and comics like
Ms. Marvel and
Squirrel Girl. There's a lot of children's fiction out there that's immensely smarter, more sophisticated, and better-made than a large percentage of adult fiction. (And, yes, a lot of those were made to appeal to adults too, but that's just the point. Well-made, smart children's fiction can be eminently enjoyable for adults, because good stories are good stories.)
A fairer comparison would perhaps be Marvel Studios vs. WB since ~2000 when the superhero craze started. By that standard, you could argue a female character was their very first movie, except that they completely threw out the character and just stole the name for a totally unrelated movie.
If you mean the Halle Berry
Catwoman, that wasn't entirely unrelated. It's subtle, but that film is an indirect sequel to
Batman Returns. It gives Berry's Patience Phillips the same basic origin as Michelle Pfeiffer's Selina Kyle (meek woman who's killed, surrounded by cats, and resurrected with a more feral personality and feline abilities), and establishes that this is a supernatural legacy that's been endowed upon many women over the ages. So it's retroactively, implicitly establishing that Selina was just one of many inheritors of the "Catwoman" legacy and Patience is her successor.