I used that 'it'll be alright, once it's finished' line recently (on the Streets of the City thread?) but I can't remember where I heard it the first time
It's such a shame that all these old buildings are going, but I suppose some of them are derelict for so long because no use can be found for them in their current format, so they get demolished (or else because they are too expensive to repair/restore). I'd have thought though that a former theatre/ballroom would have made for an ideal music venue, or even a night club - maybe the repair bill & possible listed status would have made conversion too costly or too much red tape for it to be viable.
I do get most annoyed when buildings that are in use get taken out to be replaced by stuff that could go anywhere - for instance Rich B itch Recording studios that were demolished for yet more student accommodation. There's plenty of vacant office space & the like to convert to student apartments, and not so many recording studios - especially ones with such a rich history. Just think of the outcry if they'd talked about demolishing Abbey Road or similar!