A headshot – sometimes known as a business portrait – makes an introduction, reveals your character, draws the eye, and leads people to feel that they either already know you or can’t wait to know you. Whether you are in business or are an actor or model, your headshot is a form of communication.
It’s a hint at your identity. It’s an expression of who you are, how approachable (or unapproachable) you are, and prepares people to meet you.
It shouldn’t be 2 or 5 or 10 years old because people are likely to be shocked when they actually meet you.
It shouldn’t be something that someone shot with their phone in a hurry, because that probably doesn’t properly represent you and tell your story.