My point is that in those situations, it isn't more effective than another at-will. Claiming that a low-level wizard who doesn't use it 1/3 of the time is making a mistake... I just don't see it.
You mention it only being a difference of 2 to 4 damage. First off, it really depends on how much the wizard has invested in dealing damage. With no bonuses at all, sure, 1d6 or 1d8 vs a flat 2 damage is indeed about that amount. Adding in Arcane Reserves is another +2 damage. Gauntlets of Blood is another +2 vs bloodied enemies. What about if we have a Staff of Ruin? Dual Implement Spellcaster? Implement Focus? Suddenly, we are comparing 7 or 8 damage up against 18 or 20 damage. Unless we have really poor chances to hit, Magic Missile is definitely starting to come out behind.
Do you know how MANY feats and magic items a Wizard PC has to have (and one has to have items and feats that are perfectly designed for this, i.e. no toughness or unarmored agility because the PC is focusing on damage) to get to 18 or 20 average damage at low level?
D8+5 (the equivalent of Int 20 7 damage for MM) needs +10 to get to 19.5 average damage. That's a minimum of 6 items and/or feats and typically 7.
One could technically have this by level 4, but most DMs don't hand out these types of items automatically. Or at least the DMs I have played with. They don't just hand out the best offensive damage items at low level. One acquires in our games a variety of items, not just offensive ones and not just the absolute best ones for damage dealing only.
Sure, the player might acquire several of those items by high heroic, but not low heroic. Dual Implement Spellcaster alone requires 2 magic implements and most PCs shouldn't really get a second magic implement until they get a neck item, armor, and maybe a more miscellaneous item. You're talking mid-heroic at the earliest if one reasonably follows the basic DMG model.
Yes, techically a DM could hand out perfect offensive items to a player for his Wizard, but I suspect that most DMs do not.
So let's look just as the ones you mention, Arcane Reserves and Gauntlets of Blood (likely to be in use by the time we're out of Encounters and focusing fire on enemies close to death.) We can have our automatic Magic Missile for 7 or 8 damage. Or we can deal 1d6+9 damage with a 60% hit chance - giving us around 7 to 8 damage... plus slowed. Thus, both are pretty much just as good in that situation.
Now, will there be times when the MM will finish someone off when Ray of Frost would have missed and been useless? Sure - but probably just as many times when MM will auto-hit and leave the enemy with a few hp left, when Ray of Frost could have hit and finished it.
I'm not saying MM is useless. I'm just saying it is only better than other At-Wills in a very specific set of circumstances, and those circumstances will only come up once in a blue moon. The rest of the time, the Wizard without MM is just as well off as the Mage who gets it for free.
And, honestly? The above scenario is comparing it to Ray of Frost. There are probably other At-Wills a good wizard will have that bring much more to the table.
Once in a blue moon? Like I said, my low level play experience disagrees with your armchair assessment.
And actually, I wasn't specifically comparing it to Ray of Frost (50% chance to hit if the Wizard is lucky), just any of the single target powers. Phantom Bolt for a one square slide. Illusory Ambush for the -2 to hit (which unless the foe is doing a multi-foe attack next round, -2 is rarely going to make a difference, 1 encounter in 5 if the Wizard is lucky). Cloud of Daggers for a little extra damage.
But I was talking about situations like the foe is already bloodied and the Striker hits but does not kill him, or the foe was already hit once or twice and the Striker bloodies him heavily. These happen quite often. I pretty much know that with 7 or 8 damage, the MM is going to take that foe out at least 80% of the time (unless it is an Elite or Solo and most of the time, I can figure those out). The Illusory Ambush takes him out 60% of the time.
Which is better?
It's definitely not something for every single round, hence, the reason I specified one round in three.
But if I can drop the opposition from 5 foes on round one to 4 foes on round one? You bet. Drop him, decrease enemy damage by 20% right away, and change the action economy from 5 on 5 to 5 on 4. That will save healing surges and other resources every time.
If I use the Illusory Ambush and hit, it too will drop the foe. But, there's that pesky 40% miss chance as well. And when that happens, one or more ally PCs have to waste attacks to make sure that foe is down.
Granted, I could do 7 or 8 points and he still has 3 hit points remaining. It happens. But it doesn't happen as often as MM taking the foe out because I have a good idea when it will drop a foe and when it won't. If I don't think it will, I might use a different option, although automatically taking a foe with 15 hit points down to single digit hit points will definitely set him up to be taken down by the next successful hit from most fellow PCs, low damage roll or not.
It's a team effort and one of the best ways to work as a team is to focus fire and decrease the number of enemies.
