For Humans, Skill Flexibility is usable at 1st level, whereas you have to wait until 2nd for Profession Adaptability to be useful; going from 8 free stat adjustment points to 10 helps round human characters.
Profession-wise, I'm guessing they removed some Talents and just put those abilities directly into the professions. It is helpful that a Cleric's base spell list only needs to have 5 spells from the Cleric Sphere, though some themes make even taking five Cleric Sphere spells difficult. Required subskills? Several systems have been doing this since forever.