The game still has a lot to do to improve match making. Also I don't think the game should do demotions until after 19th Dan. This will keep new players engaged in online longer I think. A sense of achievement can go a long way, demotions can be so deflating.
This is a great idea, they should really do something similar for T7. Let people grind dans with no fear of losing progress, give away some achievements for that and by the time they'll reach 20th dan they'll have some experience under their belt.