The thing sticking outside of the icon draws the eye to it, which means your focus is at the edge instead of the center, which makes for a more error prone experience.

Since the eyes are the cursor, this is a problem. Desktop and mobile don’t have this issue.

Regardless, you don't need to make the hitboxes one-to-one with the graphics. Indeed, doing so tends to make for unreliable hitboxes, so most picking systems have two different, idealized enter and exit hitboxes for each icon.