.223/5.56 is ideal for varmint/pest control, coyotes, hog, even some deer.
The only rifle round worth suppressing would be a .22. A sub-sonic 223/5.56 round is essentially a .22 in terms of power (i.e. worthless)
Contrary to popular imbecilic opinion, if the Vegas shooter had been using a suppressor and sub-sonic rounds thenmost likely FAR fewer people would've been injured/killed because the bullets would have been traveling so slow and at such a long distance they would've barely penetrated the skin instead of passing through 2 or 3 people. I'm sure we'll learn soon that the same bullet hit multiple people.