As the header suggests, this is not a description of the new online-editing facilities in Valhalla. Rather, it is a discussion about the philosophy which makes us not implement such a feature.
An area in a MUD (or in any text adventure game, for that matter) should be considered a work of art. The atmosphere of each room should be carefully crafted, and should form an integral part of the overall 'feel' of the area; no room should be thrown in simply as filling material. The intellectual effort involved in writing a truly fine area should be comparable with the writing of a short-story - this is not a haphazard venture, but something one should go about with respect and care.
With a mental effort of this magnitude involved, it should be clear why we don't consider the possible advantages of online building to be greater than the costs. Quality building should involve careful thinking about the theme of the area; mapping, and finally the writing of the decriptions. These tasks are, in my opinion, best carried out with your favorite editor (as one prejudiced in favor of Valhalla, it's easy to claim that no decent MUD-area has ever been output by 'ed').