1. It does give claims before you claim the title. It's the de jure claim of CK2. You control enough important lands in some de jure kingdom/empire and can proclaim yourself the ruler of it.I believe my method achieve the same thing, but isn't based on artificial as hell conception of "final, important title".
Why do forming countries gives claims, after all? To give country an ability to conquer its "logical" (I don't want to say "historical", because some countries you can create never existed before) territory. So giving the country special CB to conquer provinces within its logical territory would achieve the same, and tag switching would be prevented because nobody would need it.
Such CBs, which have some specific clause with region, culture or some special options exist in EU4. Unify China limit conquest by China superregion. Imperial Ban limit it with Empire territory. Nationalism limit it by attacker culture group.
2. It's by no means artificial. By claiming certain titles you bound your realm to the lands of this title. A king of Italy wouldn't randomly say "Now I am an emperor of the Mughals", just because he happens too meet the criteria. If a country has any of the final tags it means it already manifested it's destiny and reasonably won't go for any other title to replace it.