I found the above image on Pinterest and its source is acknowledged in the picture. It appears to offer a criticism of gamification as only inspiring extrinsic motivation through points and leaderboards, represented by all of extra greens on top. But the real motivation (the carrot) is very small. I agree that points and leaderboards will only motivate you for so long. Certainly, I would not invest so much time in this if were only to add some bells and whistles to my classroom. What really excites me about gamification is the way it allows me to feed that intrinsic motivation that is deep and significant. Video game elements within the classroom naturally lend itself to a mastery based system. If you don't meet the clearly stated standard the first time, you receive feedback and are challenged to try again. Each quest is tied to a standard so students know why they are doing the activity and what learning should come out of it.
I think gamification does provide both intrinsic and extrinsic motivation. Students may start off with enthusiasm for the game elements and language but will eventually come to appreciate the process and challenge of learning.