I just read the first 4 issues of All Star Batman actually and I have to say I actually enjoyed them. I'm a big fan of this 'devil may care' style Batman and think his attitude is great, I think that Morrison just wanted to depict the Batman in a new light and he has done that perfectly. As to whether or not it's a parody I think that yeah, he is poking fun in certain areas, but at the same time it is a believable character when you consider this is in the Dark Knight Universe. However I have to agree that Year One just doesn't seem to fit in this universe, unless somewhere along the way Batman just got super cocky for some reason.
I wonder if All Star Batman may have fared better had All Star Superman not been as well recieved.