Randomization and procedural generation are two interconnected terms. While randomization is mainly concerned with the application of chance-based mechanics (think card shuffling, critical hit chance, and randomized loot drops), procedural generation is focused on creating new content based on carefully crafted rules.
Let’s focus on looking at the effects of randomization first!
To be effective at prolonging your game's lifespan, randomization has to be constrained and applied in a careful, deliberate way. If done right, it can add thrills and make the game slightly less predictable, without undermining the player's ability to plan ahead. Do it badly and you'll end up with an unplayable mess where player ...