Of course she has her own life, everyone have their own life, their own talents. But Ran 'attach' to Shinichi too much, she talks, thinks, blush about him most of the time. Sometimes i feel like Shinichi is the god of her world, for example, in the recent hostage crisis case, i remember she said something like: "Shinichi won't let anyone die !", did she really need to bring up Shinichi here ?. I know it's because Ran believes in him, but it would be better if that was her own thinking, not influenced by Shinichi. That's why her character is lack of depth to me. And about the 'childhood friend disappeare', why do ShinRan fans always use this ? It's not like Shinichi's dead, Ran can call him anytime, not to mention Shinichi has promised to come back. That's nothing compare to Ai, her family is all dead, she can't even hear their voice, and not to mention others thing she has to face (you should know it yourself, i'm tired to mention them again). Yet, Ran keep crying everytime Shinichi about to leave her, that's just weak.
I wish i'm better with English so that i can express my ideas more clearly, but i tried my best.