I don't thing anyone would argue that such a strike is "uncommitted" in terms of intent or strength. I think rather in Aikido we typically train against an attacker who "commits" his/her whole body to the forward movement stepping into the nage with a tsuki, as opposed to say a jab that still it thrown with some power but it not so committed to the forward motion that the whole body moves in and the strike doesn't snap back. I think this is uncommitted we are taking about, not an attack without intent or power.
One thing I'd like to put forward it that such a strike can only be thrown from close range (a boxing range if you will), if you maintain a ma-ai that is out side that range (not as easy as it sounds) the attacker must make a committed move of their body as well to reach that range to strike with a jab, this it the movement you can take advantage of, not "grabbing" the hand.
Don't get too caught up on semantics. Phi gave the solution that I would have given in his post.