I can see some of the arguments. A lot of the debate is descending into "I don't like it, so it's a bad idea." That, and it's beginning to get very charged emotionally, which is always a bad sign for what began as a rational discussion.

Will the feature stay in 3.3? Yes. The point of a beta is to trouble shoot bugs and get a release candidate ready. Disliking a new feature is not a bug. Will everyone be happy with the feature in 3.3? No. And there's already at least one plugin floating around that forces the menu system to display in the old-style all-expanded format.

That's the beauty of an open source project - if there's something about it you don't like, you're free to make changes.