I really believe Arena net should add shields for caster professions. In Pre Searing, a lot of the npcs have shields, but later in the game, this is made impossible to have a good shield because of the attributes.
You have 4 weapon sets, cast in your wand/focus and swap to shield/martial weapon for taking damage. Shields are fine as they are and a mage shield would just promote lazy (and in PvP, even more unskilled play).
i must be missing something here. would a shield with +1(20%) to attribute not be a caster shield? i have several that i've aquired from proph and factions both. curses, domination, smiting, healing, fire
I don't think the game really needs special caster shields. There's plenty of item options for casters as it is - and in any case, a lot of casters (including me) sometimes use a shield anyway in certain situations.
I think it's fine that shields are bound to physical combat professions.