While I do agree that lucky headshots from an opponent make for really frustrating play, I don't see that as the main problem. The main problem with the wingman is that for mid to long range, skill being equal between the opponents, you basically need to have a wingman (or longbow for long range) to counter it. The person with the wingman can AD strafe very quick to avoid shots while still sending out damage. If the other person has anything other than a wingman or submachine gun, their strafing is significantly slower and the person with the wingman will be landing every shot on the ADS person.
ADS with assault rifle (or god forbid an LMG) will get you rocked in no time while the other person dodges shots. An SMG you'll at least be able to strafe fairly quick while ADS, but you're going to have trouble hitting your shots from mid-long range.
So basically, every gun loses to the wingman except the wingman in mid-long range encounters. Bad design. Not sure how to fix that, but it should be fixed, because it leads to having to always pick up the wingman in case you get in a fight with a wingman.