Normally I think it's very tough to introduce a character that is never shown on screen. But Bochco's writing (among others) was brilliant. It wasn't about the actual character of Mrs Columbo, it was a trait of Falk that went along with his cigar, trench coat and crappy car. Talking about Mrs Columbo wasn't about how she really was. It was a mechanism for him to work his observations about clues to the crime into a conversation that seemed to be innocent chit chat. He fooled people all the time setting up traps, maybe nothing he ever said about her was true. In the words of Hitchcock it was a type of Maguffin.
I think she appealed to everyone because everyone was free to see her in their minds eye, based on their own life's experiences. Nailing her down was a mistake, an insult to the original creation of her real purpose in the show. The many comments about "that's not how I saw her" speaks to that. This show has a better chance with people who are unfamiliar with the original Columbo.
As a side note, when Columbo was popular I was a police detective. I naively tried to say in interviews a few times: "you know when my wife..." It always fell flat.
