I found a few blogs discussing the trend.
At least from the TV production angle, it seems likely that they want to make shows seem "more cinematic".
One likely side effect if ultra-wide TV shows do become the norm is that ultra-wide monitors will probably become more mainstream, so you'll likely see more PC games natively supporting ultra-wide. (At least from Western developers. Expect to still have to have hack ultra-wide support into half-arsed PC ports of Japanese games for many years to come.) Also there'll probably be more budget friendly ultra-wide monitors available.Discovery Executive Producer Alex Kurtzman, who worked with J.J. Abrams on the recent rebooted Star Trek movies, has said that he specifically pushed for that aspect ratio because he’s in love with the anamorphic frame, and because he wanted to give people who were paying a premium rate for the show more of their money’s worth.It somehow does two things: it broadens the scale, making everything bigger, but it also somehow increases the intimacy. I don’t know why, it’s just the magic quality of anamorphic filming. But it has allowed us to shoot, essentially, a film now, and to eliminate the line between television and movies.
That’s really fun for us, so you’ll see it feel a lot more like a movie this season.