I think they dropped the Mr. Goodwrench brand in an effort to create greater differentiation between Chevrolet, GMC, Buick and Cadillac. Mr. Goodwrench encompassed all the brands as a "one size fits all." As we all know, GM had issues for several years with severe overlapping in their product offerings resulting in many cars basically identical except for the namplate. They have made a significant improvement in recent years with new car designs and differentiating the remaining 4 core brands. Even though Mr. Goodwrench had to do with service, eliminating that brand is part of the strategy to make each brand unique IMO. It seems like they starved the Mr. Goodwrench brand in the last few years anyway.
My. $.02.
My. $.02.
Yeah I think they hadn't done much with Mr Goodwrench in a while anyway.