We need a more accurate version
The true story of B&C is more interesting than this sliced-and-diced version (although it's a great movie in and of itself).
The story of Clyde's family and his time in jail is worth a movie on its own.
In reality, they were very low-life, two-bit crooks who lived from day to day by robbing gas stations and grocery stores, not big bank-robbers like Dillinger (who thought B&C were amateurs, as did Pretty Boy Floyd, who told his family not to help them). They had plenty of botched robberies and loads of bad luck (just hinted at in the Penn film).
There are a few accurate scenes in the film, but there is SO much other material that would make a good movie.