Maybe I just do things a little slower and more carefully than most. But the day I learned Protect my life got a lot easier as a caster. Solo, it's mandatory. I can't take hits! In a party with my friend I try to keep Shock Spikes and Protect on her constantly, it's my way of contributing and trying to prevent slowdown or a situation where I have to heal. Because healing just destroys MP.

An increased duration might be nice, but I also think that it's fine as is. I think a great idea would be for an animation to show on the spell fading. Like a shattering version of the normal effect you see when you gain Protect. This could apply to all status spells, since the icons are kinda small and there's no noticeable message when they're gone.