The range is one factor, but what really makes both ults so different that zooming Xerath's out would be bad is the fact that Xerath can shoot 360 degrees. To cover that and the range at level 3, Xerath would look like a little blue (or Red, or Green, or Yellow or... Pink) dot on the screen, and worse, his targets would be too small too. Also, Jhin's ult is fantastically easier to land. 4 shots? Check. Strike in a line and not a small-medium AoE? Check. Has increasing lethality? Check (Ok, this one makes it no easier to land, whatever). Slows target hard on any shot? Godforsakingcheck.
My 10 cents? It would be time to work on Xerath once more. The Ult`s particles are outdated and so his ult in general. Hard to hit 3 shots even with vision and experience because someone decided that Xerath should have a delay between blasts that allow people just enough time to juke them no matter how much skill (or lack off) they have.
The cooldown? Again, pretty bad right now. Lux, the most dominant long range mage on SR right now, can fire a long range super easy to land and damaging as hell laser every 35 seconds. On extended team fights she can ult in and out on the same fight. She can literally use her ult to clear a wave, go base and come back with just 10 seconds for her ult to come back. And repeat it. You can assume she has her ult all the time. Xerath, on the other hand, has up to 1 minute between opportunities to use his ult to barely kill escaping targets, because God forsake you if you try and use this ult to initiate or do anything resembling utility, like stealing something, since there is a delay between casts and no single shot can actually compete with a skilled Jungler with a smite ready.
Another thing: time to scrap the whole Stays Rooted while Ulting shenanigans. It is a relic from the time Xerath rooted himself to extend the range of all his skills. It is simply not relevant anymore. Instead, Xerath should have an ammo mechanic for his ult and be abe to shoot it on the fly as part of his combo if he wants. It would be simply better. An ultra long range fourth skill with some utility. Wanna start a fight with a shot and save the other two for fleeing survivors. Go ahead. Wanna use 1 or 2 shots to help clear wave and leave the last one for emergencies? Go ahead. Reduce a little the range (not too much. Identity, folks). About the cooldown? Make it small enough for the first charge to be almost always present, like 15 seconds on level 3 with 40% CLDR, but each other charge takes more time to prepare (25 and 35 seconds, adding up to 75 seconds to have all charges up).
There is a lot to improve there.
