Sure, aerodynamics play into efficiency once you are moving fast, so that's one reason to prefer narrow tires. Also, weight can be important, especially if you're climbing hills. Two tires of the same construction will have two different weights if they are of different widths. The wider (and heavier) tire will be harder to pedal uphill. This is why everyone has a limit to how wide a tire they're willing to use. I certainly don't want my tires to be as wide as car tires. The choice of tires is a compromise of various factors, and no single tire choice is perfect for everyone.

The trend towards wider tires in many realms of cycling is driven by the industry's breaththrough in making wide tires that are also light and supple. Many of us would not have wanted, say 32 mm tires, because they were so much heavier and slower than our 25 or 28 mm tires. But now they're not. They are still a little heavier, but that little extra weight is worth it for some of us.

And speed isn't everything. In a way, it's important, even to people not trying to go fast. A tire that CAN go fast for a strong rider is also a nice tire for slow riders because of its efficiency. It requires less effort than an inefficient tire.