What's the point in defaulting functions in C++11?

Question

C++11 adds the ability for telling the compiler to create a default implementation of any of the special member functions. While I can see the value of deleting a function,

Answer 1

As well as changing the accessibility (private/protected) of generated functions, you will be able to make them virtual.

struct S
{
    virtual ~S();
    virtual S& operator=(const S&);
};

S::~S() = default;
S& S::operator=(const S&) = default;

The following aspects of defaulted functions can be modified:

• access (be made non-public)
• virtual
• explicit (constructors)
• exception specifications
• const-ness of parameters

but to do so, the functions must be defined outside the class (8.4.2/2 in the C++0x Final Committee Draft).

A version of the original proposal by Lawrence Crowl is here.

Thanks to Roger Pate for the clarification and citation.