The mechanics of 1e and 5e are very different in effect. In 1e, your success probabilities all increase with level, often by very different degrees per class. Fighters hit twice as often as magic-users and thieves in 1e melee. Bounded accuracy flattens success chances across all classes. Ability scores in 1e mostly matter to class-specific tasks, while driving all saving throws in 5e (which are only class and level driven in 1e). In 5e, there is much hit point and damage scaling by level across all classes, whereas in 1e physical damage scaling is rare and magic is the main source, producing the linear warriors/quadratic wizards phenomenon. The result is that 1e characters play very differently from one another, while 5e characters are a bit more homogenized. This is understandable given the current focus of wanting all characters to shine in combat. In 1e, sometimes your character had nothing to add, and sometimes they were key.
I'm sure to have got some details wrong, so feel free to correct me!
I like 1e a lot, but I'm not going to call it superior to 5e. By popularity, it certainly is not. They are just quite different.