FoxFamily dynamics isn't exactly the core of the Futurama mojo. More often than not, it's a means to emphasize a character's personal drama and show how he copes with it. If you doubt it, just remember any good family-themed episode and you'll find out it explores the themes of emotional trauma and loneliness, be it Fry's memories of his long gone family or Leela's orphan childhood. It might have sounded sweet in theory to show how good as parents Professor Farnsworth and Hermes are, but the episode fails on one fundamental level: up to this point the audiences hardly realized they had functional families. Professor's clone kid Cubert and Hermes' son (what's his name again?) are among the most forgettable characters in the show. They almost never turn up in 'ordinary' episodes, they are not especially well written and even less important to the overall mythos than Maggie Simpson. So, sidelining the main trio in favour of the kids didn't play out very well. By no means the fault lies with the creators, they are great. Just the very formula of the show doesn't make conventional family relationships engaging in any way, it's simply not about this. It's about a personal journey through the strange and unknown future, not reinventing The Jetsons. It's safe to say the tiny brewing subplot was the funnier part of this episode.
