There are different cases when designers need to convert strokes to filled objects. Outlining strokes in a vector logos may prevent print problems with uneducated clients. In Adobe Illustrator strokes are measured in points and usually when you scale an object (up or down) , the stroke weight stays the same but the rest of the artwork gets unproportionally distorted. By outlining the strokes before you hand in the logo file to the client you can be sure that if he desides to scale the logo, the strokes' visual weight will always match the rest of the logo.