Gary, there are two functional reasons to skeletonize the hammer:
(1) By reducing the weight of the hammer by about half, it speeds up locktime enough that you actually get better primer ignition from the same mainspring tension setting--this allows you to reduce the mainspring tension more than you could reduce it otherwise and still maintain 100% ignition reliability. A fast slap always beats a slow crushing blow when it comes to popping primers.
(2) The actual hammer fall will feel noticeably lighter to the shooter, and "jostle" the gun less. Whether this contributes to greater practical accuracy or not is debatable, but it sure feels better. If you've ever dry-fired a 1911 with one of the lightweight hammers like the Koenig hammer made by EGW, you'll know what I'm talking about.
Yeah what he said.