For any current hardware, it is purely a convenience - you can get the same data from point A to point B with standard digital audio cables, and if you have a receiver or processor you will need at least two cables anyway (two HDMI's from source to receiver to display or HDMI from source to display and digital audio from source to receiver). I seriously doubt that folks are really stressed about that scenario.

For HD-DVD and Blu-ray, you start getting into a different situation. The only digital audio output allowed that will carry the new audio formats is HDMI - coax and optical will get you a scaled-down Dolby Digital or DTS output, not DD+, TrueHD, or DTS-HD. Without HDMI support (true support - with audio - not just video switching with an HDMI connector), we're all stuck having to use 7.1 analog audio connections (eight more interconnects). That is what I see as the source of the fuss about HDMI support.