Technology advances for every generation and seemingly every generation of old folks disapproves of the younger generation and how they do things. It is inevitable. Just because things are new fangled and different doesn't make them wrong.
Just to note, the M16 was adopted when I was in junior high school. It's been in service longer than any other small arm to my recollection in the history of the military except the 1911 and the M2 (which ain't so small). These guns have been around for a long, long time and I've NEVER liked 'em. I don't like the caliber and I don't like the ergos plain and simple. Pistol grips are for pistols. If you like 'em, great, buy all ya want. I'll let you cut in line. What I think is new and what I think has driven the sudden popularity of the AR platform in the last 15 or 20 years is war based video games.
Hell, it's even given the lowly zombie a revival of popularity. I thought the zombie lost its popularity in the 50s. Zombies have been around a long time, too, ya know, and we didn't need no stinkin' AR to take 'em down back in the day. Our Springfield muskets did the job nicely.
As for light weight, I've got a lightweight .308, a Remington M7 Stainless.
It's got a scope on it, but no sirens, can openers, flashlights, lasers, anything else. It's a HUNTING rifle, that's a rifle specifically designed for HUNTING. I don't hunt with a M1 or an M14, either, even though I know I could and am not as averse to the ergos on those rifles, rather like 'em. I've shot the M1 in our club, DCM club, never felt compelled to add one to my collection though they are neat.
I would like a M1A some day, maybe. They're pricy, though. I don't need no stinkin' picante rails on the thing, though, and it'd just be a plinker and take up space in my gun safe for show and tell.
I have a few other rifles like that that were a lot cheaper, like my eighty dollar Egyptian Hakim. That one always freaks out the unknowing.