The issue is that you are assuming he won't be in other events in the future where you can just use your free points. At the moment, you're thinking if you could have gotten 80 frags.

Oasis has done this in the past where they don't give the full amount of frags. The fact tsunade showed up more than twice in missions provides hope for him to show up. After this week, then it becomes a irrational decision in your part to use the free points on jiraya or anything else since only a select few of whales will manage to get all of the ninjas at the time they have them.

You and several others just had the expectations high. I knew they have in the past given not the full amount of frags for a ninja in one event in the past. So it wasn't a huge surprise to me. Their definition of free is not using any coupons/ingots. Since someone already did the math, your free points from missions can get the remaining frags. It's a just the typical move you should have expected rather than hoping for the best scenario.