Soccer players, for whatever reason, generally do not like wearing shin guards. It's weird. Many players go for the smallest possible shin guards in order to maximize unprotected shin surface area. Maybe it's like a weird masculine thing. I don't know.
What I do know is shin guards exist to protect one's shins from harm, and not wearing them is a fool's errand. Getting kicked in the shin hurts more than getting kicked in many other body parts, and soccer provides ample oportunity for getting kicked in the shins. You should wear shin guards so your shins don't get hurt.