Why aren’t there battery grips for rangefinder-style cameras like the Fuji X-E’s and X-Pro’s? (This is not to be confused with hand grips which do not extend the bottom of the camera (and add a shutter release button for portrait orientation shooting).)
1) Fuji doesn’t have the connections needed for a battery grip on the bottom of the rangefinder-style cameras probably due to the next issues.
2) Since people like their rangefinders small and light, adding a large battery grip is probably wanted by too small a market for companies to make a profit selling these.
3) In a word, awkward! (in portrait orientation)
If you want to maintain the viewfinder location, then rangefinders require the user to raise the right hand unusually high (like holding the camera to your forehead). This is harder to maintain on a rangefinder than on an SLR because you either have to raise the left arm much higher than on an SLR:
Or drop your head more to reach the viewfinder (while your left arm stays in the same support position).
Turning the camera bodies clockwise (so the shutter release is at the bottom) has its own pros and cons which you can work out for yourself. I prefer not to shoot this way since it takes away the major benefits from my left eye preference.