Sorcerer's have too much mobility options

Sorcerers are suppose to be focused around spellcasting and far less on mobility. Champions like Master Yi and Fiora and many Marksmen needed that mobility far more since they need to stick to their targets so they can land basic attacks while champions like Brand, Malzahar, Xerath and other mages rely on their abilities to do the job and it does not require them to have extra movement speed

For instance why would Xerath even need Nimbus Cloak to gain extra movement speed when he uses Rite of the Arcane that will make him stationary and become siege unit relying on landing AoE from huge distance?

On other hand Fiora for instance need that extra movement speed so she can pop the Vital points on the enemies and lets say Master Yi needs also movement speed cause if he cant stick to his target to land basic attacks he does absolutely nothing.

I think Precision suppose to have most mobility options of all the rune trees since its focused around agility and sustain damage from basic attacks thus you need to be able to stick to your target. If you cant stick to your target you are doing nothing