Yah, that’s the Carbine, I know.
But everything goes back to John Garand’s original template.
There was a problem with the Garand family of weapons: round output in the early days of the Chinese offensives. The Chinese were, strangely enough, more plentifully equipped with more men with more varieties of automatic weapons. It was thought that American soldiers needed to be given lighter rounds and higher volume of output. Thus, Eugene Stoner's Armalite found favor within the Army that had a baleful experience in Korea.
However, in Afghanistan it was found that lighter rounds (from say, the 9mm family of Baretta weapons) didn't necessarily put the Jihadi to sleep. So there has been a trend back to the 1911 as a sidearm. I haven't heard about a trend away from the M-4 as it is the Government Issue rifle, but it does appear that people are looking for a happy medium between round output and stopping power.