Because it's not about the movie, it's about the marketing.
Disney has zero confidence in its ability to make popular products these days. So they, along with most of Hollywood, want a "proven" commodity. A story that has proven it's a money maker.
It's not that Disney is making movies for you Baby Boomers to relive your childhood. It's that since 'Underdog' proved popular with one set of kids - it will likely prove popular with a new set of kids. You Boomers can sit around all day in your Depends as far as Disney is concered, the Mouse wants your 12-29 year old daughters.
So it doesn't matter the movie isn't anything like the TV show, the flick is aimed for a different audience. And, Disney firmly believes, old crusty shows have to be hip-and-edgy to catch onto today's audience. Anything like that fossilized boring dull TV show is out - anything that works on the Disney Channel is in.
What I don't get is why make a film named "Underdog" that has nothing to do with the tv series the boomers remember. I mean if you wanted a dog superhero you could just call it superdog or wonderdog. Didn't they have to pay someone for the Underdog name?
Just thinking of what Disney used to represent, and I'm not saying they have to always do what walt would have done because I know today is a different time and hell who knows walt may have wanted to put a dog in a cape, but like AV said: "The difference is the effort and talent people are willing to put into the project." For the record I liked the new shaggy dog movie, but I know it could have been done much, much, much better.
