JUNG1999,
I can't speak for others, but I am not using the loop when I rip a magazine out of the magwell.
My above comments are not meant in that context. When the magazine is wet, I'm cold, tired, bleeding or fill in the blank, the Magpul portion that wraps around the mag provides additional surface sticking out when I run my hand down it. If my hand slips off the portion of the mag that I usually grab, there is still a portion that my hand will grab and latch onto. Hopefully this makes a little sense when written out, when demonstrating it is pretty obvious and clear. This is the main benefit over 550 cord to me. I ran 550 for years in the service.
I know that there are instructors and places that advocate using the loop for tactical reloads and retaining the magazine, but I find that to be extended use of fine motor skills, and I am not a big fan of teaching that way.
I hope this helps clear it up, if my above rambling doesn't make sense, reply, PM or email me and I'll be happy to go into greater detail.