I think it is that CO probably doesn't see any benefit from it. They probably assume (like I do) that anyone who flies 200+ segments has to fly 200+ segments and is probably constrained by geography or corporate agreement to CO. Even though this topic comes up, none of the posters seem to be looking to move their business because of the lack of an upper tier, so CO probably feels pretty safe not giving any special treatment.

None of this is to say that some recognition might not be warranted, just conjecturing about why CO doesn't think it worthwhile.