Actually I agree.
If the default is Sybille and Sybille is the most focused archer then it should default to archer.
You'll pick up Ifan (who is definitely a scoundrel), the Red Prince (who could be warrior or mage) and Lohse (similar).
Of course when you play a second time you will know but first time it better to take the default. So the default should make sense. That is Archer.
Better of course would be to have the ability to change companions stats when you pick them up.