The monster event is heavily incentivized rewarding to newer/non max leveled players. The amount of orbs you get from doing instances as opposed to world map killing is insane. I’m not saying you should nerf instance orbs at all. Rather, increase the drop rate for world map mobs to be much higher, or allow 300+ characters to get orbs from the 290 instance.
Right now it’s really not worth the time investment to do this event at all on a maxed level character.