What's with awkwardness/fear with romance?
I talked about this a little bit with my friends at school. One of them said to me that showing public affection is considered rude or embarrassing in Japan. So this is the reason why some couples are hesitant to hold hands at first. One example can be found in Clannad: The couple once walks to school alone. One of them suggests, embarrassed, to hold hands. The other person replies "But what if someone sees us?" They are close to finally holding hands but they get interrupted by a friend.

But this is probably only one of many reasons why this happens. A guess of me would be writer laziness. But I wouldn't take my word for it.