yeah but many copies of morrowind ended up in the hands of people who had no idea what they just bought and found it boring quite soon. Oblivion graphics have attracted even more casuals who don't even know it's an rpg (seriously, i've heard them "cool ! oblivion ! i've been waiting for this to come out..what was it again ? an rpg right ? you go around slaying orcs and stuff ? cool i'm buying this ! ). Not that there's anything to worry about, except from the fact casuals represent a huge part of the market these days
Oh, anyway, i'm hearing Oblivion just got a 10/10 on game reactor : ) can't confirm yet, though.