What i think is simply that large majority of the population wants something full free and something good achievable with some effort for free within that week.
Jonin minato or obito aren't what I'm talking about because if you just spend coupons every event or only in specific events to get power ups - that's what most of the f2p people do - then there is no way they'll be able in a week to get the 12k coupons needed.
What i mean is something like pain optional gift pack at 2500 coupons by knowing that by completing all the features on show during the event you are granted to get 2500 coupons for sure.