Shimano has spent the last several years making themselves the undisputed masters of hollow forged aluminum goodness, the culmination of that being the 7900 series Dura Ace cranksets. Most bicycle components are hollow, and for good reason - hollow things tend to be lighter and stiffer than their needlessly solid counterparts. Shimano has figured out how to perfectly apply this not only to their crankarms, but their chainrings as well, which is an excellent design feature that translates into mindblowingly good front shifting. Combine that with a new and improved pinning and ramp design and it just doesn't get any better.
Let the other guys mess around with carbon molds. Aluminum isn''t outdated, it just needs to be done right - and rest assured, Shimano is doing it right.