The mall featured in the iconic Blues Brothers chase scene was located in Harvey, Illinois. It had recently closed and was left to decay for 30 years before being torn down.
I believe it was Cab Calloway who told John to not be a cover artist, and to be himself on stage, that he "had the blues".
It's nothing like you describe. John and Dan both lamented the deprecation of the Blues and these fabulous artists, and wanted to showcase the Blues (and Motown).
If it weren't for them, and that movie, I wouldn't know of half the artists whose music they used in the movie, and a bunch of others that weren't well-known (or largely forgotten) by the 80's.
That movie, and John and Dan, are credited with re-invigorating Blues and Motown in the 80's and later.