It's probably a girl thing that they want her to play up..
The way I see it, the writer doesn't want this caring and frightened girl element of hers to go away. The damsel in distress should get rescued by her knight in shining armor after all, which, in this case, is Shinichi. If and when she would be saved and swept off her feet remains to be seen.
Also, it just contrasts her more with Ai and, perhaps, Ayumi. From the episodes that I've seen, I think that Conan/Shinichi could be a combination of them three personalities. This tugs him and creates fan-base for each relationship.
Oh, well... that's just me. ^^