Aiming projectiles is kind of a pain when you don't know how wide they are.
While this isn't a high priority issue, sometimes, knowing the width of a projectile can be insanely useful. Whether you're clearing a lane or trying to hit as many champions you can in a teamfight, knowing the width of a projectile you're about to send out can really make a difference.
This is especially true for champions like
(R) who receive additional effects when they land abilities on multiple targets.
Or maybe you're playing
and you want to position yourself to make your Q land on as many targets as possible
A few other champions with this are
,
and there are probably some that I'm forgetting.
A good way to change the aiming for these abilities is to change it from the current way to something like
's R.
Again, not something that puts anyone at an insane disadvantage. Just something useful.