Quite an interesting article you have here and I would like to add some stuff.
I am ok with fun stories and I have (or Rachel played) an Amnesia Map that was ment for PewDiePie, and I admit, we had a lot of fun. Some bugs were in there and it wasn't tested fully but it was a great imperfect game. However, since my hiatus on here I have begun to get a few reoccurring warning signs of a custom story being less than stellar, or even god awful.
Quick disclaimer before anyone gets their torches and pitchforks out. I am not a PewDiePie fanboy but I am subscribed to his works. I enjoy what I see and laugh while not being a "bro". Better way to describe it would be that I watch My Little Pony: Friendship is Magic and enjoy it but I am not a "Brony".
I recently played and recorded a story and noticed a few things that have applied to those who are familiar with Felix's work. Example, the golden statue that you may or may not know as Stephano. Yeah we do have fun with it but more and more recently they have been purposely shoehorned in there for the purpose of getting a reaction and as an after effect, pad out the video a bit. Same applies to the barrels and the flying bodies.
There are ways to have said statue and barrels in the game without the whole shoehorning and make it look like it fits, but that depends on the aesthetics of the story. For example. Barrels would be more suitable in a refinery or storage compartment then say...in the middle of the floor or on top of the stairs. It did bug me that the map was mainly a "this is for Pew please play it lawledge" and the experience didn't really feel right. No opening nor conclusion. Now if I can compare it to say...Through The Portal then you get an opening via the game its based of. You know what has happened and the aesthetic makes you want to explore and find the secrets, and also wraps up the story with a small stage of being pissed of (the ending).
Stories need to be thought out. Small drawings on graph paper, the story, the notes and how they can be more than a collectable. I would like to see a story with a full on custom monster and not some pin on to an existing monster like Dark Room (which is also in my superstar tag team for best stories ever!)
In conclusion, I do encourage fun maps but they need to have a purpose than being a cry for Cry or Pew or Morfar anyone else on the Machinima/GameStation network (or others). You can still have it but you need something else. Dark Room is a great example for breaking the atmosphere while still being a great laugh and I have yet to see another map that can also do that, and if there is, link me so I can give it a try.
Also, plus 1 for Extra Credits
Lots of Love