PG_Ref wroteJust can't recall the last time I saw someone wear long pants in an organized ball game.
Religious reasons.
And, if long pants are worn instead of shorts, they are legal. If long pants are worn under the shorts, they are undergarments, and are illegal if they go below the shorts. If they're very long socks, they can legally go all the way up above the shorts. Also, there are no color limitations on long pants (if worn instead of shorts), undergarments below the waist (and above the shorts), and socks. Go figure?