I hope they will weaken this restriction, and will just not have non-sandboxed apps show up without searching for them, or without switching some "power user" option on.
Some types of applications simply cannot exist with these types of restrictions. They are removing entire classes (e.g. window managers, system utilities) of applications from the App Store with this.
But what's the real market size for window utilities? Not something your average user buys. I use size up and cinch, but I'm a developer. My dad doesn't care about fairly obscure system utilities. Besides, it isn't like those tools can't be used on ML-- just not through the MAS. MAS is a shopping mail, not a specialty shop. I don't by rock climbin gear from Target, but I'll gladly by an espresso machine from Target.
Some types of applications simply cannot exist with these types of restrictions. They are removing entire classes (e.g. window managers, system utilities) of applications from the App Store with this.