Samsung's optical drive division has a FAQ that appears to indicate that many customers are requesting Mt. Rainier support and that they are collecting customer opinion and considering a firmware update to enable it:
http://www.samsungodd.com/kor/Liveupdat ... earchMode=
Of course, that's not particularly concrete information, and is based on a machine translation (I can't read Korean).
In general, I think Mt. Rainier (EasyWrite) is stuck in no man's land. It still isn't built-in to any major, consumer oriented operating system, so there isn't much demand for it. And without much demand for it, the drive manufacturers don't want to be bothered including it.
Without built-in OS support, there really isn't a great deal of advantage to Mt. Rainier anyway. Sure, the background formatting is nice, but beyond that, what does it offer? Better defect management? That's probably not something the average consumer thinks about. And frankly I don't know how its defect management compares to that of other packet-writing solutions such as InCD.
Personally, I stay away from all packet-writing solutions, because I feel they are too unreliable. Maybe that makes me part of the problem...