Actually, there is a reason not to!
I'm rather surprised myself to discover that there is such a reason. Lately I've been experimenting with softcore. (Long time HC4Lyfe brought to softcore by the Valhalla revamp.) Now that I'm ascending softcore I've discovered that if you have a Legion Loathing Knife, dope wheels and a clockwork maid in storage you can solve the quest without ever unlocking the tinker or visiting the knoll.
You're saying right now, "Sure... but does it actually cause a problem?" Actually, yes! It's a minor issue, but I have my Quest Tracker displayed in the Character Pane. If I visit the untinker it will clutter the pane.
In other words, I hope that this feature will be dismissed by the mafia gods.
I have a wonderful override script that automatically visits the crackpot mystic to fetch his continuum transfunctioner and automatically solves the untinker quest when I have access to the knoll. I've modified the script to check if you have access to a loathing legion knife (or anything it can fold into), either in your inventory or storage. If not, then it will visit the untinker on your first visit to the woods.
Just download the attached script and put it in your /relay directory. Problem solved.