I posted this in the suggested errata thread, but thought to copy it here with the main discussion:
I think Twin Strike is the real culprit here. I think it is just too good to be an at-will.
Maybe it would be better if it only gave one attack roll, but then did primary [W] + secondary [W]. If you hit, both weapons hit. If you miss, both miss.
Or maybe a hit with the primary attack would generate a secondary attack.
I laos think it should be melee only.
However, because Twin Strike is an at-will, people compare careful attack and sure strike to it. As it stands, there is no reason to use Careful attack in place of Twin Strike. But I contend that this is a problem with TTwin Strike, not Careful attack.
For sake of discussion, pretend Twin Strike didn't exist. Now sure strike and careful attack have a place: they offer an increased chance to hit at the expense of (+mod) damage. Yeah, someone says, but the average damage per round is lower than that of a basic attack. True, but I think that is a flawed argument. The point of careful attack and sure strike is to increase the chance to hit. Sometimes you really need to hit the target, even if it means potentially less damage.