What was the point of Marvin and Wendy's participation in the SuperFriends?

What was the point of Marvin and Wendy's participation in the SuperFriends?
Wow, I haven't heard those names in a long time! In the late 1960's, there was a huge marketing push to make kids and teens look more heroic in order to be more palatable (and more likely to be watched) by kids. Many of the companies took steps by creating cartoons that centered around teenagers such as Scooby Doo and Speed Buggy. Some animators did not want to toss away successful ideas like the SuperFriends and began to incorporate younger characters into existing shows (like Marvin and Wendy). Marvin and Wendy were not very popular, as they had no super powers except for the uncanny ability to get themselves into situations that required the help of the SuperFriends. They were later replaced by the stronger (and oddly androgynous) Wonder Twins, Jan and Jayce.

This somewhat creative trend degraded into outright laziness with the idea that making existing characters younger would automatically make them better (ie, Muppet Babies, Tiny Toons, Flintstone Kids), but that idea has thankfully been abandoned in favor of again creating new, young and original characters.