Just because they got their cutie marks doesn't mean it's the end. It's as they said. They have more ahead of them. It's like after when I graduated from college. I know what I want to be now, I have all the tools, But now the challenge is using what I know to get better. Sure their crusading has ended, and yeah it is a little sad to see that go. But as sad as it is to see that part of their story come to a close. They now have a new road a head of them, new challenges, and obstacles to overcome. I do wish they had saved it until just a bit later. But I am interested to see where the writers take this next.
On another note entirely, I have a hunch; I can't help but feel that this is setting it up for something bigger down the line. Why else would they have the Crusaders find their cutie marks this early? Not just that but why would they have some of the characters reach this close to the end of their goals and arcs all in one season? You can probably call me testicles; But the writers are up to something. And Glimmer may do something rather dark if she is to be at the season final. I'm probably wrong, but it is something that is itching at me. Especially since the show is more aware of it's audience now than it was before.