Batman's other skills make him quite ubiquitous in many scenarios, but on the plane of Martial Arts...He looks like a weakling--and possibly a Squib or idiot who couldn't learn some very useful techniques.
Batman: I went around the world and learned martial arts from the greatest masters! Anime Martial Artist: Really? Do you know the Five Point Palm Exploding Heart technique? Batman: ...Partly. AMA: Can you block the chi of your opponents with precise strikes, preventing the use of special abilities? Batman: ...Sometimes I wish I could. AMA: Can channel Ki into your strike to make it more powerful. Batman: ...No. AMA: Can you do a Hadoken? Batman: No AMA: Can you flash-step? Batman: No. AMA: Fly? Batman: No! AMA: You're kinda like a Ninja--can you walk on water or make copies of yourself? Batman: For the last time NO! AMA: Wow. You suck as a Martial Artist.