Why not HDMI all the way?

[djcruiser]

Here is a question I have been wondering for a long time...

If HDMi cable is supposed to support the best picture and sound quality out the for any HD signal, then, Why don't they use HDMi from the starting point to the finishing point?

Meaning since I have DirectTV, why don't they run all of the wiring from the dish itself, down to the reciever boxes via HDMI? Same with Cable...Why not run all of the wiring for the Fios or Cable originating point to the cable box in the house?

I know with cable they would have to replace millions of miles of underground and above ground cables! But forget that that is an issue, and it was either cheap or free to replace it all!

I guess what I am getting at is this, If they can use RG-6 cable to our boxes, supplying the HD to the box, then why do we have to use HDMI cables to get the "Best Picture" and "Sound" out of said box? Aren't we getting the same signal from both in essence?