Why do the aliens in the original Space Invaders game get faster as you destroy more of them?

In the original Space Invaders game, the aliens get faster as you destroy more of them to increase the game's difficulty and tension. This mechanic creates a sense of urgency, encouraging players to act quickly and strategically as they face a progressively challenging scenario. The escalating speed also enhances the game's excitement and keeps players engaged, making it more rewarding as they improve their skills.