Shoulder pads are certainly lower profile than they were in the 60s, 70s, 80s and even the 90s. However, they are as effective, if not more so. Most have integral pads to protect the lower back and kidneys. Some have rib protection that make flak jackets unnecessary.
The major difference is in helmets and face masks. When I played high school football in the 70s, the standard helmet at virtually every level was the Riddell TK. It was a suspension helmet. There was a webbed headband riveted to the interior of the helmet. The only real pads were the cheek pads. Many players, even in the pros, wore two bar plastic face masks; some even wore a single bar; Tommy McDonald wore none at all.
Today, helmets are heavily padded inside. In the early 90s I had a helmet made of my favorite college team. There isnt much difference between the shell of that helmet, and the one I wore in the 70s. But it weighs 3-4 times more due to the padding. In addition, its equipped with a large, rubber coated, steel cage face mask.
Helmet technology has advanced since I had that helmet made. Portions of the helmet can flex to spread impact. The interior padding can now be custom made to fit to specific player wearing it. But they are all heavy, and even kickers wear some form of cage mask. They do a better job of protecting, but they also embolden players. That, coupled with the fact that players are bigger and faster, contributes to even more head injuries.
A number of years ago, a clothier in my town advocated for the return of the days of no face masks. He had played in the Big 10 in the 40s and 50s, and briefly for the Packers after that. His point is that if players faces were vulnerable, they would stop leading with the head.
I dont think we need to go that far, and rules have been enacted to discourage the practice, but it is still a problem. I dont know what the answer is, but more padding really isnt it.