Well, I guess there's a fundamental misconception of Detective Conan that needs to be cleared up so it wont be treated as a punching bag.
Drag it out? Drag what out? The individual stories are as much the main story as the arcs that surround them. You're mistaking
Detective Conan with a battle shounen. The narrative involving the Black Organization is interesting and a large part of the series, but it shouldn't be the hook. The bulk of the series are one-off whodunit mysteries and its been that way since the very beginning. And it's really shitty for you to say Aoyama is "greedy" even though there's zero evidence of that. The guy is legit into mystery and is constantly talking about being enamored by other series like it. He's clearly got a passion for it, and his series is set up in such a way that it can go as long as he wishes, so why not?
I'm assuming you don't watch the show since you're gauging progression by the number of appearances as if that's some metric by which the overarching story line can be measured. You're telling me you watched the show and you didn't get the direction it was going from the very beginning?
Let's examine the first season:
I went ahead and crossed out all the episodes that directly involve the overarching storyline. Four. Hell, in more recent years we have whole series of episodes dedicated to BO and other main story things. If anything, it's tilted
more in that direction as it's gone on.