I think you're on the nose, SMI. I'm very sure that my parents and their generation (who came of age during the Great Depression) and also their parents' generation for the most part didn't see Dillinger, Bonnie and Clyde, Ma Barker, et al, as anything other than the dangerous hoodlums that they were. I'm also very sure that their sympathy was with law enforcement, particularly the nascent FBI.
I had read in the past year that on a per-capita basis, the casualty rate for LEO in the 1930s was the highest it's ever been largely because local LEO generally didn't have the resources to deal with the criminal gangs, and also because on many occasions they were outgunned.
I also recall that when Bonnie & Clyde came out in 1967 Warren Beatty caught a lot of flak for glamorizing the couple.
All that being said, I think a lot of people (such as myself, safely removed by several decades from the crimes) take an interest in the criminal exploits of the hoodlums (although not necessarily putting them on a pedestal).