2d4 isn't that far off from 1d10. And while they can't add that single point here and there from feats, they CAN add it in from items and such.
And 1d6+int is good enough when multi targets DO apply. War wizards take Cloud of Daggers and Scorching Burst, thus giving them single and multi-target capability in their at-wills. Let's face it, Cloud of Daggers is a as damaging a power as Sly Flourish.
Actually let's do more then just face it, let's give actual numbers.
Strangely due to the way cloud of daggers work it will do the most damage with the highest wisdom, not the highest hit. Since "auto hit" damage is worth nearly double normal damage each point of wisdom is worth double each point of int which make the best cloud of dagger wizard someone with 20 wisdom and 14 int. Incidentally as a wizard you will suck even more with those stats.
Lvl 1 wizard with cloud of daggers against a target with 15 def (50% base hit), counting a +1 bonus damage from feat either staff weapon focus or something else:
-20 int, 14 wisdom = 6.875 dpr.
-18 int, 16 wisdom = 6.95 dpr.
-16 int, 18 wisdom = 7.125 dpr.
-14 int, 20 wisdom = 7.4 dpr.
A human battle rager fighter with weapon focus, 20 str, using an execution axe will hit for 9.9 dpr vs a target with 17 def and 11.1 dpr while "Raging".
2-h weapon fighter will do around that too with reaping strike or cleave.
Human Ranger, WF, 2WF, Twin Strike Waraxe: 11.925dpr. (4 feats but still, at least the feats are there to increase damage while the wizard doesn't have any he can take).
Elf Ranger, WF + Primeshot, Twin Strike Great bow: 10.45 dpr.
Rogues:
Dodger Halfling Rogue, WF + 2WF, Nimble Blade,Piercing strike , Rapier
(5 feats): 14.525 counting sneak attack but not the flanking +2 bonus. With the flanking bonus it's even more disgusting at 16.575 dpr.
Brutal Human Rogue, WF + 2WF, Nimble Blade,Basic Attack Rapier (his defense is very bad though with only 14 dex): 15.475 dpr, 18 dpr with the flanking bonus (remember that range attackers cannot flank).
Those are pretty much the highest dpr that I checked. I don't have any numbers on the barbarians or the warlock, maybe I'll do them when I have more time.
But note the following things. A rogue can easily take 4-5 feats in the heroic tier and they each add something like 0.5 to nearly 1 dpr to a built while the wizard cannot really take more then 1 feat for "damage".
Also the superior weapon feats are huge and add a minimum of 1dpr per "w" at least.
So basically, my retarded wizard with 20 wisdom and his 7.4 dpr with daggers is basically not even in the same league as the strikers in term of damage. Each time a wizard use an at-will to do damage he's basically showing everyone how much he's sucking unless he hit 3 targets with a scorching burst. At 2 targets you can at least mention it but even with 2 targets you are only in the 10 dpr range. 3 targets you fall in the 14.5 dpr range.
Wizards will scale at best like a ranger but again unless you are hitting on average more then 2 targets you are never close.