Controversial opinion:
Despite how messy the show was, "Gotham" truly captured the essence of a comic book show, embracing the campiness and absurdity that make comic books so enjoyable. Coincidentally, "Gotham" already explored the Penguin vs. Sofia Falcone storyline in its fourth season.
My issue with HBO's "The Penguin" grounding everything in realism is that it drains the fun out of the experience. It's trying so hard to be taken seriously, stripping away all the humor that made "Gotham" such a weird guilty pleasure to watch.
As you mentioned, what sets "The Penguin" apart from any other mobster show? Does this story need to be told if the characters weren't named Oswald Cobblepot and Sofia Falcone?