The correct socket is not strange, it's good thinking by Ford. When you buy something in bulk it's cheaper - that's why this socket is in every Ford.
The second advantage is that they only have to make 1 cable for their own diagnostic machines. Cheaper again.

Have a look here: http://www.autoenginuity.com/product...ware.html#EI01
That claims to have support for Mondeo TDCI's.