The real advantage of named parameters is the ability to have optional parameters as well. Which means that instead of:

   var c = new X(3, "blue", null, null, null, null, false, true, null, 1, null);

(which, sadly, is an all too common implementation pattern), you can have:

   var c = new X(foo: 3, bar: "blue", baz: false, quux: true, wibble: 1);

Which seems quite a bit better.

Another advantage of named/optional parameters is that you can use them in the construction of immutable objects, whereas you don't get that advantage if you use settable properties.