Actually, I think Ran's character is actually a loveable character. She fits to be a perfect wife in reality. Perhaps we need to rethink about her character from Japanese girl's point of view. Also, we need to understand that that this anime has been a pretty long series. At that particular point of time when her character has been established, her character was actually a portrayal of most normal girls in high school. And at that time, the idea that girls are weaker than guys are still around. Girls like her are more or less thought to be normal. So the idea to make her strong in something like karate was actually to make her a little less normal.
However, now, the situation is totally different. People do not think like this anymore. Girls are now a lot stronger than they used to be. Therefore, looking at girls like RAN now makes her a very plain character. Her actions now are deemed irritating and annoying. However I will still support her! Just because this girl still possesses the values which I believe in. To me, a person is smart or cool or beautiful or weak in heart is not as important as what I deem to be a value. So I don't dislike her.