Locked camera takes a bit of time getting used to.
When I started playing League of Legends I had mostly played games on Nintendo consoles that had focused the camera on yourself. It felt natural to use the locked camera when I first started playing. As I started getting better and better at League of Legends I started to realize the benefits of playing with the unlocked camera more and more, and started trying to play with the unlocked camera almost exclusively. It was hard at first, but eventually I got good enough at using the unlocked camera that I have no trouble now.
The biggest advantage of using the unlocked camera comes from champions with long-ranged abilities, even if they aren't global abilities. Unlocking the camera makes it so much easier to play long ranged casters because you can always stretch the camera away from you to use your ability, then put it back on yourself without having to manually unlock it to use these abilities.