Since Magic Missile does 11 darts at 9th...

I think Making this a rework of Magic Missile would be better.

Upcasting:
2nd- 5 darts.
3rd-  8 darts.
4th- 12 darts.
5th- 16 darts.
6th- 22 darts.
7th- 26 darts.
8th- 32 darts.
9th- 38 darts.

But have it be, half of the max of the missiles can hit 1 target, if there is more than 1 target enemy within range. If upcasted at 5th or higher.
Since it can damage a BBEG in a fight, or you could move in a certain way to single out a target.
38 x 1d4+1 = [133 avg] [76 min] [190 max] of a damage way less resisted than others. 

Meteor Swarm:  "A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one."
That's 20d6 2x of 2 damage types that are highly resisted. With a Save to half it all. And the AOE is detrimental too much to use it as casually, and can't be used underground.

Quote from RedrumZombies >>

Since Magic Missile does 11 darts at 9th...

I think Making this a rework of Magic Missile would be better.

Upcasting:
2nd- 5 darts.
3rd-  8 darts.
4th- 12 darts.
5th- 16 darts.
6th- 22 darts.
7th- 26 darts.
8th- 32 darts.
9th- 38 darts.

But have it be, half of the max of the missiles can hit 1 target, if there is more than 1 target enemy within range. If upcasted at 5th or higher.
Since it can damage a BBEG in a fight, or you could move in a certain way to single out a target.
38 x 1d4+1 = [133 avg] [76 min] [190 max] of a damage way less resisted than others. 

Meteor Swarm:  "A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one."
That's 20d6 2x of 2 damage types that are highly resisted. With a Save to half it all. And the AOE is detrimental too much to use it as casually, and can't be used underground.

 Magic missile does 10.5 damage at 1st level; burning hands does 10.5 damage per target, Dex save for half, at 1st level.  Then, at 3rd level, fireball does 28 damage of the same type per target, also with a Dex save for half, but with much better range and area, so a 28-damage magic missile with slightly better range should be fine.  (Meanwhile, at 2nd level, the various gold standards for one-off direct damage tend to be upcast 1st-level spells, like burning hands and magic missile, and in particular comparing Melf's acid arrow to 2nd-level magic missile makes the former hang its arrowhead in shame.)  

All the way up at 9th level, two tier gaps later instead of the one in the previous paragraph, meteor swarm does 140 damage per target--half the same fire and half magical bludgeoning, which is approximately as good as force if not better--with the same Dex save for half, with range and area as far beyond fireball as fireball is beyond burning hands; thus, mile-range, 140-damage magic missile. 

As for the argument that vast area of effect is a disadvantage on a damaging spell, what of circle of death?  Besides, meteor swarm's areas can overlap as much as you want them to, though you can't get any extra damage out of it.