It would have been funny if Trump would have responded, “CNN doesn’t need to be there. They just make up all their stories anyway. So, what difference does it make?”
The bashing of CNN here is deplorable. Of course they care and want to be there. They are professionals and perfectionists and take great pride in getting their news wrong. If they are not at the conference and completely make things up, like a stopped clock, they have a significant risk of correctly reporting the news twice a day.
No, they are better than that. They want to be present so that they can be sure of being 100% fake, and not occasionally right (by chance).