It's simply because there's no other choice. It's not up to us what the price is.
That's not the impression I get, and I've never seen that used as a reason not to import. The reasons I see, at least this time around, all come down to risk. You don't get a warranty with a gray market machine, and (per Mike above) it sounds like you can't even get out of warranty service on a gray market/imported Sony. So it comes down to a choice of "taking it in the rear" up front, or being left holding the bag if something goes wrong. Risk is a personal decision, but I would never recommend someone take a $6000 risk.
Personally I just look at it like the Japanese models don't exist.
AVS bans talking about where to purchase altogether. You can't post links, or talk about any seller (except forum sponsors I think), importer or domestic. Even then you're not allowed to talk about prices other than MSRP. It's nothing to do with importers or not.