Huh, that's not the way I'd see it.
PHB Chapter 3:
While you are transformed, the following rules apply:
Your game statistics are replaced by the statistics of the beast, but you retain your alignment, personality, and Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature’s bonus instead of yours.
So in bear wild shape, your WIS would still be +3, your proficiency is still +2, making PP still 15, and then you adopt the Keen Smell trait giving you advantage on Perception relying on smell, making that PP 20
The +3 in a bear stat block simply reflects its +1 WIS modifier and it's +2 proficiency bonus. But you're not a bear, you're a Druid in wild shape.