Keith it isn't 'just about' the joystick AF, there are a lot of things IMO that are better on the X-T2
1) AF Speed
2) Zone Focus Modes
3) Higher Resolution - can offer more cropping options as well as the obvious high res images
4) Dual Card Slots - gives peace of mind
5) Better Shadow Recovery
6) Better at High ISO, I've had decent images at 12,800, which I couldn't get on the X-T1
7) ACROS - very good, very film like at High ISO
For me its just a much better user experience, and I certainly enjoy using it more than the X-T1, not that the X-T1 was a bad camera, for me the X-T2 is 'just better'