Robert Harris has offered to restore the OOT FOR FREE! There may be other costs associated with the restoration, but I imagine it's not happening because Lucas either has zero interest in bothering, or it's an ego thing.
But something is seriously wrong in Lucasland. The format wars are over and it's time for a hi-def release. He can't even be bothered to take his existing hi-def transfers of the 2004 Special Edition (which have aired on TV in HD) and simply dump them onto a bare-bones Blu-Ray.
The Lucasfilm reputation for a quality, cutting-edge product is pretty much gone. But yet they still can't get anything out the door, other than re-re-re-released DVDs.