I've got Cooper Xeon asymmetric all seasons I use on the Subaru for the summer, and Hankook studless snows on now. The Cooper tires replaced some directional summer tires that came with the car that were awesome in the wet. These aren't quite as good in the wet, but are close. I'm not partial to the Hankook snow tires, but they work better than all seasons in snow and slush. The price was right, and they were available when I needed them. They seem as good as the Goodyear snows on my Son's car.
I think asymmetric tires might be of some use, the Cooper tires I've got look like they have 2/3 summer looking tread with big plain blocks, with the other 1/3 looking like a regular all-season. Maybe it buys enough use to call it an all season that is a summer tire at heart.
I think everyone has certain things they like to see in a tread pattern. I can't say I know if it makes any difference in a car tire.