If that was the case, in other words, if they had truly broken one of the arches and that meant the entire display was therefore inoperable, then come out and say it. In fact, they could have come out, been straight, said we had an accident and the LoW will not be displayed this year. However, at this time, we will be using this opportunity to fully update and upgrade the LoW so they will be back next holiday season bigger, better, and brighter than before.
There: you were honest, addimitted you made a mistake, but also go on to say that you're going to make the situation better. That would have been fine and I think 90% of us would have understood. But no, thats not what they did, mainly because I think the story that an arch "broke" is BS.
And even if they did break an arch, it does not mean that entire LoW is "obsolete." Heck, Disneyland's SM broke (Literally! A piece of the track fell off!) Did they declare SM as an attraction obsolete and just forget about it? No, they went and upgraded it and made it better than before.
There is no excuse that is logical for this situation; Disney screwed up, and screwed up big time. The sooner they realize that the sooner they can get to making things right.