It's worth pointing out that Samsung isn't necessarily keeping compatibility with Gingerbread as they are keeping compatibility with their own TouchWiz version of Gingerbread. For the most part, this is old news. It's reasonable to assume that if Samsung is going to saddle Gingerbread with proprietary UI "improvements", they're going to do the same with ICS. The fact that it lessens the difficulty of switching from one version to the next is an unintentional side effect.