Opteron

- Buttons like dedicated ISO dial, metering, shooting mode etc.
- Viewfinder magnification (0,77 vs 0,62)
- Horizontal tilt of LCD screen
- Joystick for focus selection (instead of touchscreen though)
- Dual SD card slots (vs 1 slot)
- UHS II support (vs UHS I)
- 1/8000 mechanical shutter (vs 1/4000) 
- 1/250 sync speed (vs 1/180)
- Buffer size (@8 fps JPEG: 83 vs 62 frames, Lossless compression RAW: 33 vs 25 frame Uncompressed RAW: 27 vs 23 frames)
- Boost mode / vertical grip advantages: headphone jack, 11 fps mechanical shutter, 30min 4K, 100 fps viewfinder, AF speed, blackout time, shutter time lag, shooting interval (see here)
 
Looks like a long list, but considering the price and the fact that there are no differences in image quality, it is a really good value deal.

- Buttons like dedicated ISO dial, metering, shooting mode etc.
- Viewfinder magnification (0,77 vs 0,62)
- Horizontal tilt of LCD screen
- Joystick for focus selection (instead of touchscreen though)
- Dual SD card slots (vs 1 slot)
- UHS II support (vs UHS I)
- 1/8000 mechanical shutter (vs 1/4000) 
- 1/250 sync speed (vs 1/180)
- Buffer size (@8 fps JPEG: 83 vs 62 frames, Lossless compression RAW: 33 vs 25 frame Uncompressed RAW: 27 vs 23 frames)
- Boost mode / vertical grip advantages: headphone jack, 11 fps mechanical shutter, 30min 4K, 100 fps viewfinder, AF speed, blackout time, shutter time lag, shooting interval (see here)
 
Looks like a long list, but considering the price and the fact that there are no differences in image quality, it is a really good value deal.

Every camera and every lens is a compromise. If the Fuji x-t2 would have a touchscreen and IBIS, it would still not be a perfect camera, because everyone would laugh at the 2500 dollar/euro price it would likely be. And just because some people desire and can affort to buy such X-T2 doesn't mean it is a profitable proposition for Fuji to create such camera. Same with lenses, the Fuji 90mm F2 is an outdoor portrait lens for good light and with its quad linear motor great for moving subjects. Just because it is a prime or F2 doesn't imply that it is meant for lowlight photography. Other primes generally work fine for me in lowlight. 
 
Maybe my experience with lowlight photography is limited, but I don't know what I would need IBIS for. Either I photograph still life and use a tripod if I really want to keep my ISO at 200. Or there are moving subjects in my frame, generally people, which require a 1/60 shot to freeze them. In the latter case, IBIS is not going to improve the 1/60 shot significantly. Photography is a creative proces and choosing the right camera/lens and knowing and compensating for the compromises which the manufacturer had to make is part of the job. I see Fuji photographers being profitable in nearly all areas of photography. So if my shots are bad, I blame my lack of creativity to get the shot right and do better next time.
 
If you demand perfection at any price, then maybe Fuji is not your system.

At some point in the future I want to explore the video functionality of my X-T2 as well. I was looking at:
- Feiyu MG gimbal http://www.feiyu-tech.com/products/31/ (around 650-800 euro)
- Sirui video monopod http://www.sirui.eu/en/products/monopods/ps-series/ (around 170-300 euro voor monopod only, 150 euro voor fluid video head)
 
Cheaper option is a steadycam, like the Ringlight Steadycam Stabilizer S40 for 150 euro.