The issue of Martial Arts was raised on 20 April. In both cases, it was Iago that responded. So let's see how much longer it will take them to make changes to Martial Arts, if at all.
What you're going to need is a breakdown of how Martial Arts falls short. So far, the only issues that have been cogently raised are the core stunt (which was addressed by Fred), and Killer Blow.
If there's something else, or you don't feel Fred's answer is insufficient, we need to know what and why.
Here's my attempt at elaborating on the case of the core stunt.
'Martial Arts' isn't necessarily just mean eastern Asian fighting styles; that's just a generalization like so much in the system.
Comparing the Fists 3 + MA character to the Fists 5 character, you're looking at a combination of training and skill versus simple raw output potential. Since we don't have a complicated stat system as a basis, we don't have things like a strength stat as a backer for melee attacks. Our analog is just raising the skill higher on the column.
The advantage that the MA tree has over the Weapons tree, is that your fists can't be taken away from you. You can't be disarmed without being dis-
armed (pun for effect). This inherently makes it a more generalized set of stunts. Just think for a moment about the Dresden books, and how often Harry has something taken away from him mid-fight. Someone with more unarmed potential doesn't need to stop and get their gear back; in their portion of the narrative, they are always ready to go.
Personally, I'm inclined to agree from my vague recollections that Killer Blow is possibly too weak for the total costs and the raw situational nature of it. What else in the MA tree suffers from this, or is this the only real egregious example, and everything else is kind of on the line?