In the same sense, it makes sense to shoot vertical if you are certain that your content is going to be consumed on a smartphone. So adding it to the M50 seems like a good idea considering the target demographic.
I look at things on the phone in horizontal orientation quite frequently. Rotating the phone 90º is not that monumental an effort. Besides a lifetime of seeing movies and TV, the experience of having two eyes arranged horizontally makes that seem more intuitive.