Since Japanese people have painful memories of having to learn to use chopsticks from the age of three, it’s possible that they are sort of overestimating how hard it is to learn to use chopsticks. I don’t think that it is meant to be patronizing.
ETA: It is important to remember that Japanese people (for the most part; there will always be assholes out there) really and truly are appreciative of foreigners who take the time to learn the language and the culture. I think that the “ohashi jouzu” thing also contains a bit of “thank you for learning to use chopsticks” as well.
ETA 2: By the way, the correct response to “ohashi jouzu” or “nihongo jouzo” is to say そんな事ありませんよ。(sonna koto arimasenyo, which means “Not at all.”) Responding in this way not only disarms them, but also shows that you know the social norms (in terms of demuring when complimented).
