I'll add one thing, which I didn't state earlier because I assumed it was obvious. But I'd like to make it clear.
What is the purpose of dragging a body and body manipulation in this stealth game?
In my opinion, it is a "tool" or "game mechanic" that gives the player the ability to do two things:
The last 10%. After shouldering a body and dropping it in a desired location, the player can drag and hide it more precisely in the shadows. Is just a foot or hand sticking out into the light? No problem. Grab and drag it into the shadows. No need to shoulder and drop the entire body again. That's a good thing. Dragging gives fine-tuned control for that scenario.
Nearby shadows. After KO-ing a guard near a dark area, the player can quickly drag the guard into the dark area. The distance here would be one or two body lengths away. Given that the distance is short, dragging is quicker than shouldering and dropping. That's a good thing. Dragging gives a quick way to hide a body in that scenario.
In my opinion, the 2.12 controls enhance the experience for those two scenarios, because the controls give a quick way to grab a body, drag it into position, and release it quickly and precisely.
However, most of the time that fine-tuned control is not necessary for this stealth game. Shouldering and dropping a body can work well enough, hence why it became the primary action. That said, being able to precisely drag a body is a great enhancement to just shouldering, and it's something players can learn and appreciate given time.