Most likely, cost savings, one less step in manufacturing and since they already make the mag cap drilled and tapped, why not .
I see they do it to some 20 inch barreled 590's as well and recall a few 500's that had the sling stud on the barrel band and not the magazine screw , as is common now.
On the 14 inch barrel, I don't think it makes much difference, but its definitely noticeable slinging a 20 inch barreled one.
If you're looking for other options, GG&G make a nice forward sling point that fits under the mag cap , for push button base, sling strap or a h&k type hook , the magpul para clip will work with the last one .
