The Apaches perform flawlessly doing what they were designed for. They were NOT designed to absorb incoming. Evading missiles and rockets from distant foe, are in their bag of tricks, but not ground fire, bullets, from close encounters.
Look at the construction of helicopters. It's the same, light as possible, construction as any aircraft. Trying to keep something airborne, weight is diametrically opposed to that end.
Military aircraft usually give the pilot/crew a little armor, if they plan on coming close to the ground. They also try to keep critical things like hydraulic lines, out of harms way.
The Apache is narrow, with the pilot sitting behind and slightly above the co-pilot, for a smaller head-on target. It's also pretty small when you remove all the weapons systems hung on the outside. There is damn little protection for the people and few places to tuck critical things, safely.
Certainly, up close and personal, barrages of small arms fire were not in the scenario when they designed this ship, although they made it quite capable of taking out large or small groups while "standing off". When the Apache was designed, in circa 1974, evidently the Army wasn't planning for the operations they're seeing now. But given a choice between a rifle or an Apache, I'd take the chopper.
Most aircraft are not designed to absorb a lot of punishment. The notable exception being the A-10 Warthog, with it's titanium bath tub the pilot sits in. The A-10 was designed and commissioned by the Army, much to the ire of the Air Force who were envisioning nuclear war and supersonic dogfights.
The Comanche design was composite sections like the new 787. Easier and cheaper to make and assemble. It's role was to be replace the myriad of light helicopters the government buys with a basic airframe that could be outfitted in different configurations for different roles.
The dirty little secret of helicopters, all of them, is that every hour they fly, requires many man-hours of maintenance. Some require many, many man-hours. The Comanche was to cut those hours down, plus ease the training and parts budget by having one airframe. They spent billions developing it then decided not to build it, but some of the technology is being transfered to other programs.
Added thought...When the military talks about winning ground battles, there always seems to be a defined enemy and more importantly, a front line. That's not the case in Iraq. I doubt it ever will be again.