The main reason would be for the HD video 1080P otherwise component can handle the 720P signal.

Seems odd to me that if a receiver has HDMI inputs it should support HD audio in some form, I guess some very early HDMI compliant avr's might not support HD audio.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70