I used to live in a London borough where there seemed to be a lot of empty buildings. I'd lived there for years and would see buildings left to go to ruin through neglect. Two buildings became occupied by squatters (one was an old house and one was an ex-Post Office). They became lived in. The house suddenly had a garden at the front and was well kept.
On the bus one day I saw a group of people outside of the house with loads of things on the pavement, including a TV and other bits of furniture. On the way back, the people were gone and the windows were all boarded up. Someone had evicted them. Talking to a friend who worked at the council, it turned out that the house was owned by the council and they were squatters. Two years later (I then moved so don't know if this is still the case) the building was still empty, boarded up and covered in graffiti.
As far as I know, the squatters in the Post Office are still there. They'd certainly improved the look of the place, and were apparently taking care of it.
So, AIBU is thinking that a safe, empty building should be occupied if nobody else is living in there. When there are so many people living on the streets, isn't this a good thing?