To be more on topic though(Copy/Pasted from my post on Eorzeapedia):
Movement canceling spell casting is an old concept and is widely accepted as a standard for many MMO/RPGs; However; in a more action oriented environment such as XIV where movement is key (would be more important if lag was not an issue.) I feel that being able to move while casting would play into the style better than stationary casting. XI got away with stationary casting because the battle system was not nearly as action oriented. There really was no constant movement other than the fights that required kiting, and even then for the most part Mages could stand in the middle of the kiting area and reach their target just fine. XIV's Ifrit battle is a shining example of why stationary casting (and animation lock) are counter intuitive of the battle system and style of play they are trying to create.