It's d6 behind WH and has a better added effect. If being d6 behind means it is doing "diddly" then WH is only 3.5 damage more than "diddly". That doesn't even make sense.
Having a damage die to roll is a big deal. Without one you can't get much in the way of damage bonuses. 3.5 extra DPR is not all that trivial either. Especially when you're talking DPR 5 say vs DPR 8.5. I don't think that WH has a better effect either. That's a matter of opinion. They both have effects that in many cases will be marginal and could come in quite handy at different times. WH is the better spell.
Plus quarry and any weapon bonuses, crit bonuses. And the W can be d12, or brutal or whatever.
Except at d12 you're now comparing a power plus a feat to another power. I can increase damage from WH with feats too. Quarry is an added class feature of the ranger. He's a striker, his damage SHOULD be higher. DB also can get bonuses from the implement you use just like TS can get them from a weapon. You're stacking stuff on one and ignoring it for others and trying to compare a striker to a controller. DB is overpowered for a controller at-will if you ask me.
What about wizards makes it so they should have worse at wills than invokers? Do they have a daily at level 1 that is so good that the other 95% of the time they should be completely overshadowed by the invoker? Not that they do.
Ummmm, you haven't run a wizard have you? Flaming Sphere is practically a guaranteed encounter destroying power in a LOT of encounters. It can and will rack up loads of damage. It is ONLY the best daily at level 1 in the game, hands down. Go to 5th level. Stinking Cloud is again the best daily at its level in the game, hands down. Yeah, wizards are REALLY gimped. Sorry, not if you know how to play them. It is certainly a harder class to play well than the "easy mode" Invoker, but if you know how to do it the wizard rocks hard. I don't think WH is radically OP, but it is definitely breaking the power curve for wizards.
You know, you can even have an enemy flanked, drop a burst beside it and still not have any allies in the burst, right? You have to be seriously cluttered with allies in order to not be able to place burst 1s effectively. "Enemy only" is very nice to have and something that wizards are missing out on compared to other classes, but it doesn't put the power over the top.
Sure, sometimes you can. Lots of times you cannot. More to the point though its VERY common to have a choice of dropping an "all creatures" and only being able to hit 1 target vs an "enemies only" where you can hit 2-3 targets. That's the critical difference. I'll take a 25% damage reduction so I can hit 2 instead of 1 as a no-brainer. If that happens HALF the time then the enemies only spell was worth it. And as I said, you can always take say Scorching Burst as well for the other situation and have the best of both worlds.
WH really should be trimmed back a bit. It overshadows ALL other wizard at-wills and wizards really do not desperately need better at-wills. Wizards can trivially pump up their at-will powers a good bit with a single feat and with 2-3 feats they can make them a LOT more potent. Invokers at heroic can't do nearly as much in that direction. I still say you really cannot legitimately compare at-wills between classes, it just doesn't make sense. The whole concept of saying WH is not OP because DB is better (which is itself a marginal call) fails to understand that the at-wills of the two classes have different balance points.