I don't like anything that forcibly relocates my camera, since I'll generally be clicking somewhere and then have the camera jump and end up clicking somewhere I didn't want to. Kalista ult already throws me off immensely (no pun intended), I don't want jhin ult to wobble me as well.
You can still see jhin while ulting, so it's just a matter of keeping an eye on the edge of the screen where you are as well as the cone where you're aiming. (And y'know, not ulting when you're in a position to get flanked is also wise.) The minimap is also still there while ulting, so you can keep the corner of your eye on that as well in case trouble shows up.
(Also even if I do get caught out, more often than not I don't want the camera centered on me, I want the camera centered either on whoever is trying to flank me or in the area where I'm retreating to, so while it might save you a half second of pressing space, it'd cost others that much or more to move the camera back to where they actually want it, and theres no nifty hotkey for those other camera spots.)