I love dungeons, but I don’t think you need them.
A dungeon should be the last thing you prep.
If I hear “want to play a one shot?” the answer is no, unless it’s a game that I expect to wrap up dramatically by the end of the session.
The particular layout and contents of a dungeon are its least important parts.
I am not interested in playing or running games unless I am compelled by the fictional situation.
The fictional situation need not be complex or “deep.”
A compelling fictional situation is a character who wants something risky very badly + things (people, obstacles internal or external) that might make him reconsider.
Example: a paladin that wants to right injustice + a lord with many men at arms who wants to perpetuate injustice.
Example: a fighter seeking to atone for past mistakes by helping people + an isolated family besieged by a monster.
Both of these would be satisfying to play. Neither require dungeons.
Dungeons enhance supplementally the enjoyment of the game.
Yet when choosing how to spend one’s prep time, one is far better served making situations to care about and helping the players make PCs they care about.
The reason normies enjoy trash boring normie D&D is that they spend time making their PCs and feel an investment in them that overcomes the faults of the game itself.