I look at the grip situation, as you describe it in your first paragraph, from a diametrically opposite viewpoint. By designing the X-T1 as they have Fuji have allowed those who want a small body with a small grip at the front to have one. If a larger grip is needed then they provide two of different sizes so that the desired size of body grip can be obtained. This allows the grip size to be tailored to the owners preference. If the largest grip were fitted as standard then that is the only choice. It is possible, as now, to add to a camera grip, but impossible to make it smaller without severely damaging the camera.
I have the largest grip fitted to my camera for normal use, but like the option of removing it when the camera has to be as discrete as possible.