Once you reach Six Paths - there really is no reason to go into arena for anything other than your 2 daily quests or a new ninja.

Adding a small reward per win i.e. 25 arena tokens would however fix this and will have people actively entering the arena trying to gain tokens.

Considering rare-er characters like Hidan are 1k/5 fragments the 25 arena tokens per win aren't a substantial enough amount to make a huge difference, and will allow players to actively participate in arena without feeling like it's pointless and a waste of time.

Arena in my opionion is a great system that allows players to develop team and strategy building skills and shouldn't be tossed away after the first month or so of play.

Edit 1: Another option would be having a random ninja selected from your roster every say - 2 hours with whom you have to win a match for say 100 arena tokens. This would again keep the arena a fun and dynamic place for people who enjoy even 4v4 PvP, while also preventing highly optimised teams from constantly bashing on people in order to farm arena tokens with the above mentioned suggestion in mind.
This post was last edited by RiusSensei at 2016-8-17 17:05