INF Soldiers are rather mercs than anything else.
About M4 and Minimi:
Mostly rifles are used on single shot anyway, cuz it needs just 3 shots fired in less than a second is enough. Fullauto is for suppressing, or for weak round SMG's.
I´m not sure about all INF rifles, but exactly the single shot domination is leaking in INF. I try to fire the G36K on single as fast as I can and only get 2 shots per second, thats very slow. You can fire singl shot as fast as you can pull the trigger and that would make single shot excellent.
Vega-don said:
not all the players want to use the "OMG THE BEST OVERKILL GUN"
Since my first INF time, I still use the M16A2 on single shot (sometimes AKMS), also like the shotgun.
My opinion is just that:
Fast trigger pulling supports single shot, a shouldered (unaimed) weapon position with smaller freeaim supports single shot when not aiming.
INF has a hipped position with huge freeaim, that makes spraying more effective than single shot guessing. Sure you can use single from hip very effective, but extreme and fast situations in combat are something different than on a shooting range.
I know it was said many times and it would require a total concept change, so it is more for INF:Source.