In the book it's because they run out of ammo because there are so many of the mimics and they are so good at killing them because they keep reliving the battles. The "battle axe" as it is supposed to be is further enhanced by the powered movements of the suit which is necessary to smash into a mimics carapace.
I just don't understand why the suits would be open. If they can devise a mobile power source small enough to make these suits practical, they need to slap some armor on them Starcraft style to protect the soldier.
Part of the aspect is extra strength, endurance and mobility but the other aspect is ability to carry heavy weapons which combined with various types of rounds would make any armor negate the benefit of said suit. In other words, the armor would have to be so thick/capable due to the increased weapons the weight would makes the suit worthless to the point they might as well be in a tank.
US military turns to Hollywood to outfit elite troops | Fox News
Armor wouldn't do shit. A tank for example has 4 FEET of depleted uranium as armor. 1-3inchs of whatever, at best, wouldn't help at all. A 50 cal rifle would pierce it. Nevermind space age weaponry. Ventilation, and mobility would be more important honestly. Adding armor would add alot of weight. Suddenly the power armor goes from lets say 1000lbs, to 3000lbs. It can no longer enter buildings, etc.
Every time I see some mention of this idea, I think of the court scene in Iron Man 2 with the tests and I cringe.
