This story does not suck, and I like it. You write well, grammatically, and clearly, and your tone or style was a fit for this kind of story. Good work!

I wouldn't be adverse to a prequel, either. n.n

I think a prequel would be in order, maybe even continue the story :O

I've been toying for a while with Conan finding out that he's actually "cursed" to end up in the vicinity of murders because when he was actually six he wished to become a great detective and the power that heard his prayer helped him by making sure he'd get lots of practise. The problem is, it's not enough for me. I'd also want a plot to go with the twist.

I don't know anything at all about the other series, but you wrote this well enough that it was still very enjoyable without that knowledge. Let me be the first to congratulate you on an interesting story written well.
Actually, this story reminds me a bit of another fic in this section called "Voices" or "Voice", I can't remember which. If you haven't already read it, I would recommend it.
As for the prequel, well, why not? I think it would be amusing.
Again, good job on a grammatically correct, interesting and thoughtful oneshot.