He goes into detail about the issue he has with all of interpretations of his Rugrats as confident, handsome, hip, beautiful people. Because he doesn't believe that those characters would grow up to look or act that way. It's pretty interesting actually because he goes into the show and how the Rugrats and their parents are average looking people and how the babies would grow up to be average looking as well...
It's kind of interesting to see how Molinsky interpreted the Rugrats. It's almost disarming and childhood breaking. It does seem very appropriate that some of the characters look "down-and-out". The main four look like the most sad of the bunch but it seems real-to-life. As much as we want to believe that our childhood heroes (whether they are fictional or real) will grow up to be attractive, beautiful, and successful.
Even though it seems like a bit of a bummer, I think it's important to remember this about our own lives. I think that we all have this idea of ourselves that we'll grow old and become beautiful people, or something, but that's usually never the case. It's part of the reason we (I mean, I, me, just me) wait for a high school reunion. We want to see how all the popular people have become unpopular in their appearance or career.
I don't know if that's a necessarily bad thing, either. I think it's something that's natural and human to compare yourself to the people around you. And maybe, it's a little fucked up to find your happiness in other people's transformation into something less desirable.
But we're all a little fucked up and I think that's okay