Set value to @State in init function

I want to pass a value to a property marked with @State, and it doesn't work.

struct AView: View {
    @State private var content: String?
    var body: some View {
        Text(content ? "")
    }

    init(content: String) {
        self.content = content
    }
}

#Preview {
    AView(content: "Test")
}

But if I change the content to non optional, it works well.

struct AView: View {
    @State private var content: String
    var body: some View {
        Text(content)
    }

    init(content: String) {
        self.content = content
    }
}

#Preview {
    AView(content: "Test")
}

I googled for a while and found that I need to use a spacial way to initialize @State property in the first case.

init(content: String) {
    _content = State(initialValue: content)
}

It works, but why? Is there any difficulty to unified API between optional and non optional @State property?