To repeat again the above. Blizzard is not allowing us a higher movement speed cap on items because certain classes (using skill and shrine) can break some technical speed limit and result in complains of "black screen". The higher the limit allowed, the more frequently players will start to experience desync from servers.
Thus my suggestion for this issue; remove the 25% item speed cap, impose a 200% character speed cap instead. The character cap is the total movement speed by all items, skills and shrine. It also doesn't have to be 200. It can be higher at 250% depending on what blizzard feels is acceptable.
Thus for the slow classes (Wizard and WD) lacking spammable movement skills, they can decide to tackle the issue via stacking items with movement bonus. This is NOT FREE movement speed. It will come at the cost of DPS or EHP. But at least the option exists.
As for the fast classes, they have the option to continue as before (that is using skills which buffs movement speed) or they also can stack items with movement and have the option to use other skills.