Every change introduced by Facebook brings out critics. When you have 750 million users, it’s inevitable that somebody isn’t going to like something. With f8 2011 set to get underway in a few hours, however, the backlash against the latest round of changes seems particularly intense. The new news feed, with its newspaper-like presentation, is attracting much of the criticism. But a deeper critique is also emerging: Facebook is trying to do too much, and is losing focus on its core mission and value proposition. Perhaps its just ordinary growing pains, but perhaps it’s a sign of more serious trouble ahead.