Are we obligated to choose noble professions?

Nope.

Should people choose noble professions, or should we do what we love?

There's more than enough time to do both. Choosing a career doesn't have to be a lifetime contract between yourself and society. You're free to mix it up whenever you want. The prospect of choosing a college major often makes you feel pigeonholed into the idea that a career has to be a lifetime thing.

After the military, I started out with a career I thought I'd love because I'd been doing that kind of work for fun since I was very young. I didn't end up loving it so I went into a "noble career" I don't particularly love, but makes me happier, in the abusive relationship kind of way. And I plan on switching it up again next year. Not because I want a good career or a noble career, but because I want an interesting life.

And as someone who has participated in war, I can't recommend war journalism. You probably know that it can be horrible, but you don't know how it's going to affect your life.