Can Ronan of the Wild use Pico himself?
Yes, this does mean that Ronan cannot use Pico's ability himself.

How is this balanced? Pico's ability grants something that, while it sounds minor, is actually very significant: several free actions. 

In a typical Descent map, there will be around 6-10 search tokens, meaning that to collect all of the tokens the heroes will collectively need to spend 6-10 actions during the course of the game. These actions are not used for other purposes, such as Attacking to remove enemies, Moving to progress through the map, or even Resting to recover temporary resources like Fatigue. The cost of gaining the gold and effects associated with those search cards is the opportunity of doing something else.

By giving any other hero the ability to complete Search action for free this is recovering those 6-10 actions for the players, allowing them to be used for clearing monsters faster or recovering Fatigue or Wounds. Combine that with the fact that Ronan himself is a Scout archetype who can take the Treasure Hunter class, and you now have a single character that nearly eliminates the opportunity cost of searching for the entire party.

So to balance out that powerful ability, FFG decided to limit Pico's power to only apply to other party members, making Ronan a Party Support character that compliments other characters rather than standing out exclusively on his own.