Still ran in Shonen Jump, which back in 2009 surveyed that most of it's readership was under 14 and specifically targets young boys. Though it also boasts high appeal for elementary and middle school girls as well. (These are a bit older in terms of surveys but the core demographics haven't really shifted from what I can tell.) Dragon Ball Z has always been Shonen. If it was truly meant for older teen/adults it'd be listed as Seinen. I honestly scratch my head at the 'it's not for kids' argument. It's okay to like something that's targeted to people lower than your age, and in different culture at that that has different values and ideas for what is acceptable consumption of media by minors. Stuff like Dragon Ball in particular ave universal appeal that can be enjoyed by all ages. There's no shame in liking it whether you're 5 or 50.
Moving on stuff like what 4kids did is pretty out of the norm and frowned upon these days in the dubbing industry and in fandoms at large. Just look at the flak Netfix got for taking Precure and turning it into Glitter Force. These days as the world turns more towards global awareness most companies strive to bring authentic representations of the media they're adapting to their audiences. Adapt, but don't change beyond the recognizable seems to be the motto.
Edit: I also recommend checking out Mary Cagle's comic about her experiences teaching English in Japan. In one she pretty clearly notes that her elementary students were pretty addicted to watching Attack on Titan.
https://www.marycagle.com/