... need to level your character to a higher level so you can get the high level rewards before the event goes away and you have to pay real money to get the items later..
Nah. We don't need more FOMO.
Events are fun distractions. I didn't enjoy the Yokai crossover BECAUSE it was a crazy grind that took forever (and at the time was potentially never coming back). I think they're doing fine with those events that have interesting activities you CAN repeat but don't have to if you don't want to and still get the "big" reward. Such as the halloween mansions and valentines maze, it was there if you wanted to keep doing it, but you didn't have to.