thats typical of like every dslr camera too, some have settings where you can go 16:9, but its standard on all cameras I've used, unless I am so out of the camera game, but my Nikon D5300 are way!
If you want to take 16x9 pictures, the camera + app has that feature. Since I view my pictures most of the time on my iPhone or my TV, I prefer the 16x9 ratio. I wish the standard camera app included that option.