Did you mean to say that "adding concentration to magic missile would make it *worse*"??? Because requiring concentration when casting it is a strict nerf.
It would make it better because the spell would be more balanced compared to other spells of that same level It would add to harsh restrictions of spell selection. Magice missle wouldn't be so op anymore you coudn't just shoot it and still have buffs on.. You know more balance? in turn it would be better, don't you think? Combat balance is more important that player fun, right?!
1.) I don't concede that magic missile is OP currently. It is guaranteed damage, sure, but Sleep (if enemies couldn't wake others via shoving), Thunderwave, Chromatic Orb, and Fog Cloud are all great 1st-level combat spells too. Hopefully Larian will implement Shield too.
2.) Okay, so you're saying that it'd make the
game better by being more balanced. I disagree. Concentration would make Magic Missile weak to the point of uselessness.
Also it makes no sense for magic missile to have concentration. It's an instant spell that is over the second after you cast it; what's there to concentrate on??
You have to concentrate on hiting multiple target's that not easy thing to do.
Witchbolt can be instant spell one turn only as well by click on concetration and turning it off, but you can't cast it without concentration.. so that could work same for magice missle!
But if that bothers you too much they can add a bonus effect to magice missle, if you have concentration you can throw ONe magice missile at a target with your bonus action per turn.
Witchbolt has concentration because it lasts for multiple turns, where you can deal the damage once per turn at the cost of your action. Magic Missile happens instantly; literally in the spell description it states "the darts all strike simultaneously." Adding Concentration to Magic Missile is a HUGE nerf - it will practically never be used beyond level 2 because there are so many better spells that would take up your concentration slot: Blur, Darkness, Enlarge, Fear, Fly, Haste, Hypnotic Pattern, Slow, etc.
As to your suggestion...that'd only be reasonably powerful if you could send 3 missiles when you cast the spell, and then 1 missile every additional turn. If it was only 1 missile on the first turn, it'd be incredibly underpowered for the reasons I said above - the Concentration requirement is too restricting. Even witchbolt would be almost strictly superior to such a a concentration-required-1-dart-per-turn-magic-missile.
Well it's a missile nonetheless and those fly in arcs and missiles normally go up first and down after so they don't hit things like trees.
The arc of a physical missile depends on it's speed. The faster it is, the less it arcs over a constant distance due to gravity. So the missiles could just be going very fast, and thus arc only a little.
Also, Magic Missiles are "magical force," so they might not even be affected by gravity! But this is a personal aesthetic choice for me and you, so not much more to say here.