Why do they matter indeed? If you want to be a stuntman/ stuntwoman, you gotta know your training. You have to learn how to fight, how to safely handle guns, how to properly do stunt work among other things. Example: Keanu Reeves learned kung fu, jiu jitsu, wires, gun training for his role of John Wick. Angelina Jolie did a lot of physical training for her amazing Lara Croft character. And guess what? Those actors are badasses! Not only is stunt work fun, but it also helps you get in shape, it helps you push your limits that you didn’t know were even there.
Maybe you want to be like Adrien Brody and learn piano, like he did for “The Pianist”. Not only did he learn a new skill, but he went fully into his character, which is called “method acting”, and I’ll talk about that later.
Personally, learning special skills like riding a motorcycle or learning French is fun, but also educational. It will definitely help you book roles. I cannot count how many times I see casting calls for people who speak fluent Mandarin or Spanish. And guess who is going to book those roles? Actors who speak those languages.
In conclusion, the more special skills you know- the better and there’s a higher chance you will be THE ONE who gets chosen for the part. Rather than people who don’t.