Frenzied Attack: (Requires Level 13) - When wielding two weapons, the Monk has 20% increased critical strike chance and 30% increased critical strike damage.
Superior Skill: (Requires Level 15) - Increases precision by 20%.
Weak Spot: (Requires Level 20) - Increases critical strike damage by 100%.
So this is clearly pre-emptive, but making some VERY moderate assumptions about gear it seems to me that for a pure damage build a crit focused monk is the way to go, in large part because there's only a handful of non-situational damage increasing traits otherwise.
Note that at low levels it's probably worth less, but once you start getting higher gear levels you can afford to really focus on +crit/precision and +crit damage gear.
Some quick assumptions here: I've heard that at base level the bonus damage on a critical hit is 50%. Let's assume crit damage is multiplicative like it is in WoW.
=120% damage on a crit from traits alone. (170% if we assume it's additive, but I think that's unlikely).
Now, there's a screen shot floating around of a 2 handed barbarian weapon with +30% crit damage on it, so it's not unreasonable to assume we will be able to get AT LEAST +30% crit damage from gear (probably much more, but I'll play it safe).
So at this point with some moderate assumptions we will be dealing +156% additional damage on a crit (or 256% of base damage).
So let's make a silly assumption here just to emphasize how big a number 156% extra damage on a crit is:
Let's assume we're starting with 0 crit rating - we never crit, ever for some silly reason.
Now we get a piece of gear with exactly 1% worth of crit rating on it. That's a full 1.56% average damage increase.
Now, from traits alone we get 20% crit chance, we'll probably have something like 5% base line and since we're focusing on crit/precision gear I think it's pretty safe to assume we can get AT MINIMUM 25% crit rating from gear (again, assuming we're going for crit all the way).
If each point of crit is worth about 1.56% increase damage from baseline and we can push 50% crit in high end gear - that's (50x1.56=78) a 78% increase in average damage with no conditions other than being spikey/slightly random.
And that's assuming we can only get 30% additional crit damage from gear, which seems pretty unlikely to me given that we've seen 1 item which gives 30% additional crit damage ON IT'S OWN. I find it much more likely that we'll probably be able to push our crit damage up to 230-250%, which makes each percentage of crit worth 2.3-2.5% of our baseline damage.
At lower gear levels it'll probably be safer to go with a straight attack / conditional trait build but crit and +crit damage scale AMAZINGLY well together.