Default Template Instantiation

[Jonathan Marler via Digitalmars-d]

If you have a template where:

1) All parameters are optional
2) The parameters cannot be deduced

Would it be reasonable to instantiate the template with the 
default parameter values? For example:

template Foo(string str = "some string", T...)
{
     class Foo
     {
         // class implementation
         this() { }
     }
}

auto foo = new Foo!()(); // OK
auto foo = new Foo(); // Error: cannot deduce template parameters

In this example, there's no way to deduce the template parameters 
for Foo, however, since they are not specified, would it be 
reasonable to just use the defaults?  str would be "some string" 
and T would be empty?