Just to put this in some sort of perspective, soldiers have been carrying 30-35 kg of "kit" for thousands of years. Greek Hoplites had tht amount of bronze armour, shield and weapons (and generally a slave to help them carry it and put it all on prior to battle). The Roman milites carried a similar amount, including chain mail or segmented armour, pioneer tools, rations and water canteen. Knights and men at arms in the middle ages had similar loads (and men at arms generally had no horses and fought on foot).
The only exceptional period seems to be the 500 years between the large scale adoption of gunpowder weapons and WWI, where PPE essentially vanished from the battlefield. By WWI, soldiers were again carrying huge amounts of "kit"; we have all read about British soldiers going "over the top" with up to 80 lbs of equipment, ammunition, rations etc.
Perhaps the introduction of superstrong synthetic materials and highly capable mini computers/communication devices rivalling the size and shape of an iPhone will reverse the trend (but then again we could be in the situation where I started: When I was a private I carried 100lbs of really heavy stuff. Now with modern technology I carry 100 lbs of reallylight stuff....)