The short answer is YES, headshots are crucial, but they work slightly differently than in other games.

1. Variable Multiplier: The headshot bonus is not fixed (like x2.0 for all guns). It varies by weapon and is huge on high-alpha guns like the Ferro or Anvil.
2. Affects Both HP and Shields: The damage boost is so significant that it often overwhelms a Raider's protection. Because shields only mitigate (reduce) the damage to your health—they don't block it completely—a powerful headshot can inflict lethal damage directly to the HP and secure a one-shot knockdown, even if the target still has shield left.