I DON’T KNOW General Motors’s vice president of global design personally, but I can tell from the driver’s seat of the new Chevrolet Blazer RS, Mike Simcoe needs help.

Mr. Simcoe, an Australian national who came up through the ranks with GM Holden division, became global design boss in 2016, replacing the retiring Ed Welburn. Mr. Simcoe’s fresh eye and exquisite sideburns had made me hope for better things out of GM. But as the new Chevy Blazer midsize crossover makes evident, he has no more pull with the accountants than...