I'm not sure that there is a really reasonable reason for HDMI to component conversion outside of a source player, but that doesn't change the fact that the movie industry has concluded that allowing any sort of outboard manipulation of a digital video signal (such as to convert to analog) is too great of a piracy risk. It's related to the (equally screwy) logic that defined component video output as "the analog hole" in their anti-piracy security (perhaps because component video pre-dates more modern security measures like HDCP and thus can't effectively be made to support new, more severe measures), resulting in both HD-DVD and Blu-ray offering the image constraint token (ICT) which can be enabled when mastering an HD-DVD or Blu-ray disc and will result in component output of that 1080p source to be capped at 540p (one fourth of the original resolution). Internet consumer outrage has kept any studios from actually using the ICT, but it was still included in both specs and can be used.