When was the last time you saw a "Morrowind" option not lead the polls?
Maybe combat system? The guaranteed hit system, I can live with. Graphics?
You guys are neglecting the possibility that maybe it's just widespread opinion that the mechanics found in Morrowind were that much better and or fluid than Oblivion. I vote widespread for Morrowind, not because I'm a Morrowind fanatic, but because I truly believe it had the better system. Likewise in this case. Show me a thread where you believe Oblivion SHOULD have won; whether you find one or not, that's still derived from opinion. Furthermore, you're make the assumption people are voting blindly with no evidence.
Plus, it's easier to explain which game system an individual preferred rather than explaining the separate mechanics.