I think though that we can go a step forward.

I agree that we all should look at it much more in a symbolic and metaphorical way than a logical way (there are several points in which the internal logic is severely weak).

And exactly because of all the reasons you mentioned above, I've always considered the whole movie being representing something related to Cobbs.

Cobbs is the one receiving the Inception.

No matter if by God or Ariadne, or God through Ariadne or viceversa. Or if this happens in the real life, afterlife, parallel life, dream levels or what. The whole movie is about Cobbs and his subconscious. It's also interesting that Nolan used the name Cobbs for one of the characters of his first movie, Following, in which Cobbs was some sort of serial burglar. Just to keep the metaphor going.