Every adventuring party has one wizard who treats their spellbook like a restaurant menu where they only ever order the chicken nuggets. Despite having access to world-bending chronomancy and reality-shattering illusions, they default to those three little sparks of glowing purple force. It is not a lack of imagination but a profound commitment to avoiding manual labor.
The Comfort of Never Missing
Roll to hit is a terrifying phrase for someone with four hit points and a physical strength stat comparable to a wet paper towel. Magic missile offers the ultimate bureaucratic loophole because it simply works without any dice-rolling anxiety. When a terrifying bugbear is charging down the hallway, nobody has time to calculate spell save DCs.
A Severe Case of Mana Shortage
High-level spell slots are reserved for emergencies that never actually happen, much like saving your high-grade potions until the final boss and then forgetting to use them entirely. Our webcomic characters constantly struggle with this exact hoarding mentality, choosing to throw rocks rather than expend a level-two slot. Until a dragon actually shows up at the tavern door, expect nothing but low-budget magic.