Maybe I'm mellowing with age or I just like a lot of the players on the Boston team but for me, at this point, it's an AL/NL thing. I really do NOT like the NL.
I think though I am somewhat representative of a lot of Yankee fans compared to Boston fans. Yankee fans (IMO) have beaten the Red Sox down so much that when an ABERRATION like the Sox winning happens it's not that big a deal as for Sox fans who HAVE been beaten down and laughed at by Yankees fans (with superiority complexes) and have bought into the curse thing so much that when they DO finally win it is their right to be insultive and exhibit large amounts of braggadacio.
In the final analysis what it comes down to is that the Yankees have been superior to the Sox for so long that when an ACCIDENT occurs it is just that, an ACCIDENT. For Sox fans, it is like the second coming of Christ.
But then again maybe it's just the purist in me and my age. I just don't hate them that much. I agree with your NFL take though but I can't remember (damn Alzheimer's) if I ever rooted against someone because they were MY team's "sworn" enemy.
Do NASCAR die hards root against someone? I guess so if one is to judge by the Jeff Gordon "hatred".
Must be me.