A real M4 weighs about 6 1/2 pounds. A real LSAT weighs just shy of 10 pounds. Neither is heavy unless you are a 90 lb. weakling. Where do people get the idea that these weapons are heavy? Have they just not ever held a rifle in their hands?
And, the ADS time, in this game, for LMGs is slower than ARs, as it always has been.
Your assumptions are wrong on so many levels.
Please at least attempt to do some research if you're going to try to be an expert and claim something should be nerfed.