actually that is how it works (watch the presentation again - they are called entitlements) you buy a game you will unlock different items from your home and incarnation. You will still have to buy some premium stuff but things like R:FOM wallpaper are likely to be free.
I think it would encourage sales of items for your home in Home and encourage sales of games if people were rewarded for their game purchases instead of having to buy all of the non standard content. IE Register your R:FoM game in Home and then have access to the R:FoM wallpaper that was shown at the GDC without having to purchase it separately. Yes some items seem to come standard with Home as far as decoration goes but why not give that extra push and include a Chimera statue somewhere in the home or maybe a Flow themed coffee table, etc. I think it's a realistic idea and would be simple enough to implement.