To add a new element to the game, but I agree it needs to be tweaked. It would be very cool if they managed to introduce some kind of risk and reward system with the mega-evolutions. I really love how Youkai Watch uses the bottom screen to perform special attacks. It's really cool, I wish Pokémon did something similar because it doesn't seem likely that Youkai Watch will ever be localized. :(
And I made a jab against Sonic games because they're the prime example of games ruined by poor gimmicks.