COD appeals to a wider audience on consoles because its maps and gametypes are suitable for 4-player splitscreen deathmatches, whereas Battlefield just isn't built for that type of gameplay, hell it doesn't even have split screen. There's still a lot of console players who don't have their console online, and they'll likely automatically ignore BF3. Whenever I buy console multiplayer games for any genre, I MUST have split screen or I don't buy, so if I didn't have a PC, I might have bought MW3 after all.
PC's not quite the same though (small offline deathmatches aren't a concern, those who only play offline are more likely to pirate, not saying ALL of them do but it is true), and so I thought BF3 had a chance of beating MW3 there. Sadly that clearly isn't the case.
On the bright side, I just fired up BF3 today and noticed a drop in the number of douchebags who go solo in the land vehicles or who run around caring only about k/d rather than the objective.