I'm not saying that you absolutely must implement OP rewards into the game. I'm saying that we are expecting more engaging events. Shugo Tomb,Trillonerk's Gold Vault, Rukibuki Circus, Gift of the Alchemist, or similar.
Put those for 2-3 weeks. Add some interesting mechanics to them. For example if you complete Shugo tomb 5 times, you get L120, if you complete it 10 times you get tempering, if you do it every single day during the event duration you get something unique like a mount. Those are not "OP" items, but just another layer for active players to participate in the event.
Btw, just as a side thought, I think you and some active players should gather around in Discord or something and discuss what events are available to us. We could surely come up with something exciting when getting closer to Halloween and Christmas events.