IMO, this kind of marketing is targetting people who don't know watches, just to remind them that watches may be an important accessory / toy.
For the rest, no, I don't see Ambassadors, at least these ones, useful.
But there is another question: Aren't we, PuristS, the best ambassadors?
Let me elaborate: This F1 Champion, Basket player, or Actor is not necessary known as a watchlover and WIS. So, what is the value of him or her wearing a Watch?
This is not the case with us... When we say we love a Watch, there is more value, because we also can say " No, sorry, we don't like this Watch ".
On another side, I remember how I fell in love with the Rolex GMT Master... Thanks to a Thomas Magnum episode where he was looking at his father's Watch, during the burial of his father.
I fell in love with the Watch, not because Thomas Magnum was wearing one, but because I saw, at this moment, a Watch which I found super cool and very much my taste.
Best,
Nicolas