hm.....i agree with you to some degree....
but this goes back to the whole...wall anime fans vs. creators of the anime. Fans are only walling or basing original drawings on anime extractions because they want to promote and show their support for the work. Creators....just want their work protected.
Most respectful wallers will tell you that, if the creators of the anime told them not to use their work in wallpapers, they would stop. (I don't remember very well, but I believe there was some discussion and action on this from CLAMP?) Sadly some wallers are getting lazy and forget to credit the original works since....they think it's obvious in certain cases.
I think it's only fair that you always label and mention the original work done by the original creators. But I think it's going a little far to make people get permission from the original owners of the work if it's quite a large amount of work...JUST to get a wall done. (IE: contacting the copy right holder of commercial anime, etc). Of course, if it's work from someone the average person thinks they can contact (online anime/managa artist) then yeah~ get their permission. But in the case of EAO's galleries, most walls are made using commercial anime extractions.