Marketing is an, um,
interesting thing.

I remember there were plenty of toys and kids' marketing around Terminator 2: Judgment Day and the original RoboCop. Maybe the Alien sequels too, but I can't recall exactly.
But that was
after the success of
Star Wars, when every genre movie was trying to copy its merchandising juggernaut. And so movies that weren't intended for kids tried to copy the marketing of a film that overtly was intended for all ages. After all, most of the films you're talking about were R-rated, while
Star Wars was PG. They're not equivalent. You're talking about exceptions, no the norm. The abortive
Alien toy line is universally recognized as an inappropriate idea. Nobody has ever thought that about
Star Wars toys.
Again --
I was there at the time. I watched this evolve as it happened. When I saw a mother bring her small child to see
RoboCop 2, it was self-evident that she hadn't done her homework about what kind of movie it was. But there have always been tons of kids in the audience at
Star Wars movies, including me, my sister, and our contemporaries.
I mean, hell, a large part of the reason so many people in the '80s expected every sci-fi movie to be a kid-friendly adventure is
because that's what
Star Wars was, and the runaway success of
Star Wars colored how the entire genre was perceived from that point on.