They may not be super great talents, but they are useful, IMO.
First, regarding pure success chances, a fortune die has a 1 in 3 chance of resulting in 1 success symbol.
The Conservative die has a 1 in 2 chance of having the same result.
The Reckless die has a 2 in 5 chance, I believe, but can result in double success symbols which a Fortune die cannot do.
So saying a Fortune die is better then a Stance die is false. Just depends on what you're looking for.
And I would definitely let these talents permit you to convert stance dice beyond your stance limit.
Lastly, roleplaying wise, these talents define your personality and demeanor, which Fortune dice don't. Fortune dice represent pure luck or the favour of the gods, not what your character is made of.
When my players choose talents, I always tell them, don't really mind the mechanical effect, just see if the Talent name fits your character concept and inspires you. Remember, talents also represent your characters influence on the party when you slot them in the party sheet.
Slotting Ambitious on a Party sheet can become a nice roleplaying moment as you describe how your character will make the other members more success oriented and competitive in the marketplace…
My two cents.