Just a question--who owned the copyright to "I Spy"? Didn't they have to OK the movie that was based on the TV show's name and supposed concept? Did they read the script before that happened or just allowed it without having done so? Or, do TV show titles lose their copyright like prescription drugs lose their patent (after 17 years)?
As for "The Avengers" movie, which has been considered to be in the running for the top worst movie of last century, you know what's terrible is that I have read the original screenplay for the movie. It was VERY good, so much better than the poorly edited garbage which came out (let alone Fiennes plays Steed as well as my petite self could play "The Terminator".) What happened was that the great script went through the devastating Hollywood system and wound up the trash it did. Very sad. The only saving grace was Macnee's Invisible Jones character.
It sounds however, like the "I Spy" movie began with folks who simply didn't even care to replicate the intricacies and character traits and interactions that the TV series personnel were so committed to. I think that's almost sadder than something starting out gold and ending up landfill; starting out willfully embracing trash and ending as a trash failure shows a complete lack of professional caring. They seem to not even care their movie tried to destroy something so previously unique and wonderful.
Tatia is right that movies based on TV shows can do well or sink, but it seems more important to know the thoughts and emotions of those converting the shows into the movies, than how big a blockbuster it turned out to be.