If I am remembering correctly, the doors at AKL are already decorated. I think it's a tribal drum. (Might be a shield - one side of AKL is drums the other shields) I would not decorate it more than that. The doors are wood, not metal like some of the other resorts. Each door is already personalized ; the designs were hand made and individual. (shields are hand carved)
Doa search for kidani doors and you can find an image.
INSIDE the room, what I would suggest - if you have kids- leave some stuffed animals/dolls on the bed. Even if you are adutls only and have, or get, a stuffed animal type toy- leave it out in plain sight.
Because of fire hazard. Don't know if that is correct, just what I heard. I thought it was interesting, cause I sure thought they were wood 
Insteresting, does anyone know if the restriction is for the protection of the animals at the resort. Or is this something that is limited at all resorts?
I think that seems more like a "value resort" thing to do.
Yep, in my experience people at the values decorate their windows since the values have exterior walkways and thus big windows. When we stayed at Pop, I would say probably at least 50% of the windows were decorated; however, I don't know if everyone did their own decorating. We didn't do anything, but out Mousekeeper decorated ours (with stuff we already had in the room--like princess costumes, stuffed animals, wands from CRT, etc.) and added to it every day as we brought more stuff back every day. My daughters LOVED it and honestly, they were let down by lack of decorating when we stayed at the Poly on our next trip.

Insteresting, does anyone know if the restriction is for the protection of the animals at the resort. Or is this something that is limited at all resorts?
All deluxe resorts for sure. Things seem to be looser at the values, maybe in between at the moderates, I'm not sure. It is not related to the animals at AKL - it is related to the fact that Disney tries to make the hotel's theme apparent in the hallways, and most guests want to see that theming, not other guests' random stuff on their door that might not be that tasteful - at least that's how I feel.
Here is the notice that DVC members received last year before the holidays (but it applies to more than DVC):
Resort leaders offer holiday-decorating reminder
As Disney Parks and Resorts reflect the spirit of the season with a winter wonderland of holiday decorations, many Disney Vacation Club® Members are decorating their villas in similarly festive fashion.
While Disney Vacation Club welcomes the use of safe decorations that don't damage the finishes of the villa, resort leaders are reminding Members that all decorations should be contained within the villa interiors and therefore shouldn't extend to the balcony or other exterior areas.
This policy, included in Members' condominium documents, is designed to help preserve the carefully crafted architectural stories and visual themes for which Disney Parks and Resorts are famous.
The Hubby & I got engaged at WDW and we made a cute lil sign while staying at WLV and taped it to the door on the outside. We did use a small tape and made sure it would not hurt the door. Then when we came back to WLV for our honeymoon we had another sign. No one said anything to us about it. We also were very carefull with the tape and made sure it was simple. I have seen some windows done up for the holidays with lights and such, which i can see how that could get "ify".