S.W.
Are these activities optional? Yes. Are they valuable? Yes.
My daughter and I started training in karate when she was 5. I have earned my black belt and she is now two steps away from the same (brown belt with black stripe) at age 10. Does she love to go to class? No. Does she love karate as much as I do? No. Does she want to quit? No. Because she told me "If I quit now, I'd always know that I didn't finish." Bingo. That's an important lesson to be learned. Once she earns her black belt, she will stop going to karate and continue with other activities that she likes more. If she had HATED it when she was 5 or 6, I wouldn't have made her keep going. If she didn't excel in it (which she does) this may have also gone differently.
The lessons she's learned in karate - the body awareness, strength, balance, and concentration - have helped her do well in other activities. Circus is her new latest favorite! And she recognizes that.
She is taking piano lessons. She also does not love this. BUT, the musical ability she is learning has made learning to play the tuba (which she does love) faster and easier, and now that her piano skills allow her to play more complex pieces, she is enjoying playing more.
I don't believe in forcing children to take lessons or be in a sport. But, the lessons it is possible to learn from these activities are valuable - focus, skill, and especially accomplishment. Accomplishments don't always come easily, they take time, energy, work, and persistence.