Surecast is bad because you usually shouldn't be getting hit as a caster, at least in group content. With the exception of a few endgame fights, it exists as something you can use if you think you MIGHT screw up in the next, what, 10 seconds?

How about modifying surecast so that it is prevents interrupt on one spell for the next minute? If the buff duration and the spell cooldown are the same, it essentially protects you from one interrupt per spell cooldown. You could keep it up constantly, not because you are planning on getting hit by something you should have dodged, but just in case you screw up.