Hmm, this is new. I would guess the purchase incentive is a discount - as in a $10 meal would only cost $9 of your meal dollars which makes them go further and makes plan more valuable. But this is only a guess - call or post question on dining FB page. You’re probably not the only one with this question.
Note with dining that you can always increase your plan if it doesn’t meet your needs but can only decrease plan for next semester, so start low based on how you think you’ll eat knowing you can increase it after semester begins. Also, someone told me the best advice given during orientation was to look at schedule of classes and see how they fit swipe periods. It may be obvious that you won’t use the plan the way you think you will. We started with a 16/wk plan but dropped down to 10 or 12 second semester of freshman year - D would rather eat cereal in her room than get up earlier than needed 
so breakfast swipes not used as much.