Harry Potter and the Chamber of Secrets is all about—who else?—Harry Potter. That's why it makes sense that we see everything from Harry's point of view. That means Harry is in just about every scene.
Wow. Daniel Radcliffe never gets a day off, does he?
This works because it totally limits us to what Harry knows. We in the audience can't figure out anything until Harry figures it out. When he finds out a new piece of information, we find it out, too. This keeps the mystery of the Chamber of Secrets going until the very end.
Think about it. This movie would be a whole lot different if we were seeing things from other points of view. If we were hearing the story told by Dumbledore. Or Hagrid. Or even Hermione. Truth be told, we'd be a little bit bored waiting around in the hospital wing for the last third of the movie if we were going with the Hermione point of view.