Mission Architect function: Doppleganger NPC
I thought about this, too, when it was first implemented and I was running the missions on Test. I reluctantly decided that as I can already costume, power, and name as I wish (effectively creating a dopple) true doppleganger tech is one of those things that I would like to see remain a Dev specific tech and not move it into AE also.
It's true you can already create model-copies of your own characters and put them in as a Contact, ally, enemy...etc. But that would just be THAT character only, not a true doppleganger that copies the person playing the mission. Dopplegangers change to match the leader and any team-mates of theirs, but the regular critters you make for a contact or boss remain static to the costume you designed it in the first place. Sure you can make an arc specific to you only so you appear to be the contact, but if it gets published and your friend plays it, they'll see your character talking about if you are them.
As for what devs consider things to be 'dev-only', wasn't it only a year ago that story-arc and custom critters were dev-only tech?

Home server: Victory
Characters on: Victory & Virtue
My first 50(0)! 18/11/11
@Oneirohero
By no means am I saying it will not happen, nor that some cool things couldn't be done.
My personal thoughts are just that there are ought to be some tricks that are unique to non-AE fare.
I know cutscenes are pretty dev-only, unfortunately the negative reaction of earlier uses of cutscene probably made a lot of people aversive of even wanting to use it, never mind experiencing other people's attempts at doing so. Plus in comparison cutscenes would be much harder to simplify over the interface.

Home server: Victory
Characters on: Victory & Virtue
My first 50(0)! 18/11/11
@Oneirohero
In light of Issue 17's hero and villain arcs, I think the next wave of Mission architect improvements and additions should include a Doppleganger NPC designation.
For instance, you could choose 'your doppleganger/yourself/self' to be the Contact of a MA story arc, which means that whoever is the leader of the arc will appear in place of the contact whoever they are. This'll finally allow people to create arcs that simulate that YOU are the mastermind or taskmaster of your own schemes and investigations and the contact is just a way to think to yourself.
It can also be used to make missions involving Praetorian counterparts (or more generically, you from another universe or time) so you can set the doppleganger as an ally to help you or an enemy much like the i17 arcs to fight against.
It might be also an option to set an enemy group that is made entirely of dopplegangers, with increasing and decreasing strength based on a particular doppleganger's enemy rank instead of being an Elite Boss like developer arcs. While most bosses will use the leader's model, if there's more than one person on the team, other members will also get dopplegangers, especially in the case of using dopplegangers as a enemy group.
Home server: Victory
Characters on: Victory & Virtue
My first 50(0)! 18/11/11
@Oneirohero