You have to have either come from (as I do) or know a military family where you can sit around and chat about these things kinda like off the wall if you know what I mean.
I've seen movies like "Kelly's Hero's" or " Hell Is For Hero's" or "A Walk In The Sun" or "Full Metal Jacket" ... guess you have too.
So we don't do maneuver warfare anymore? Iraq anyone?
If you are going to be consistent finally, you can't compare a 5.56 shooting SAW to an M60 which fires a larger projectile. The M240 is the same caliber and its average weight through out the variants is comparable to the M60.
Granted most of the infantry is mounted nowadays in desert terrain but they are dismounted in urban terrain and hump those guns under fire sometimes for many days. They also wear more gear than the average WWII soldier. The MG is far from a defensive only weapon any officer who used it strictly in a defensive manner needs to put his head in front of it.
A task such as carrying a MG twenty miles may not be part of the current curriculum when we have control of the sky and V-22’s to fly grunts and humvees to transport them from point A to point B.
But there may come a time when an enemy has wrested control of the sky from us and rendered our transportation by air or ground unsafe or non-existent, and carrying in your arms an MG of any make or model twenty miles may be the only way to either accomplish the mission or live to fight another day.
We won’t be fighting against entities with no air power, satellites, drones, smart weapons or offensive capabilities forever.
Regardless of how many technical goodies we have, direct combat still boils down to the most exhaustive physical activity anyone is likely to encounter in their lives. Even today.