Well if you think about it there are going to be what another 3-4 BB's of various types in this house. They are going to give it a different style each time and even move the rooms etc round a bit.
So why spend thousands on furniture etc when it's only going to be used for 2 months.
Theres two things I'd be wondering about though.
1. Surely some of the things are either totally wrecked or damaged in some way so how much are they relaly worth (ignoring the potential 'celeb' value)
2. What about these people hiring the house for £20,000? They will be hiring out a shell, the furniture and diary room chair gone to the baliffs, The Sun had the 2 plasma screens in a competition today, I would guess most of the odds and ends and even things like wall panels were taken for souviners by 'cast' and crew so what on earth does it look like now???