Sometimes you have to level up your gear in order to have more fun, and honestly playlist activities are pretty fun sometimes. But I gotta change it up, I can't just grind out 4 gambit matches in a row if I'm getting tilted by invaders or something. I want to try out the new raid, and I'm currently at 930 power (938 w/ artifact). So I need a bit more, and then I'll be ready to go. So yeah, that's one reason to do milestones.