When I'm playing in game as a caster or with a caster (sorcerer and wizard obviously) I almost "always" hear some complaint against Magic Missile. To be honest, I don't dislike Magic Missile, but I do think it's missing some of the better features it has in the Forgotten Realms, and PnP.
First off let me make one thing clear, I do NOT want the damage affected. 1d4+1 per missile is set out in "every" version I've read so far and I'd rather not make an overpowered Magic Missile Spell.
Anyway here's what I think magic missile should do when a player casts it:
*A party is fighting a mass of oozes in the sewers the targetted ooze has 2 other oozes adjacent to it
1. Level 9 player casts Magic Missile at a targetted ooze with a little hp left.
2. First missile hits the ooze inflicting 5 damage
3. Second missile hits the ooze inflicting 3 damage, ooze dies
4. One of the adjacent oozes is randomly chosen by the spell
5. Two of the missiles hit that ooze and it dies
6. There are no adjacent enemies to that ooze, the last missile is wasted
So basically if one enemy is killed before all the missiles are used up, they target another enemy. I don't think this suggestion deviates too far from the PnP version or overpowers Magic Missile, just adds a new feature to a spell that really isn't as good as some of the other evocation spells (niac's cold ray can hit for 20 damage at level 2 and burning hands basically has the limit of range to the number of targets it can hit)