It was an asset back then to have a style that set them apart from other actors. Look at Humphrey Bogart, for example. I doubt he'd be a successful actor today, but back when uniqueness was a virtue, he and many others with unique looks or speech patters, he was popular and even considered attractive. John Wayne, was also unique in the way he talked and walked.
A lot of actors and actresses spoke with a Transatlantic accent, which was kind of a merging of elitist American speech with a British accent. Carry Grant, Kathrine Hepburn, and many other spoke with a Transatlantic accent.
Today, everyone just want to be pretty, or so it seems. The pretty people are the only ones who matter.