Every player is different. Our son began switch hitting in college and continued throughout his pro career. He's a natural lefty, who always hit from the right. His college coach encouraged him to try switch hitting.
Switch hitting improved his value by giving college and pro coaches more options within one roster spot. Also, it allowed him to better utilize his abilities...power from the left and average from the right. Whenever he slumped, he always felt he was slumping from both sides. Finally, it was one more tool in his box that helped set him apart from the competition.