I agree soverylucky that constant tinkering with the education system doesn't really help anybody - least of all the pupils. However, on the subject of the buildings, the last government build loads of shiny new school buildings and standards continued to drop. I don't think you can blame external factors only for falling standards. Some (not all by any means) bit some, has to be down to the quality of teaching.
Equally, problems in society that you allude to - yes, it causes no end of grief for teachers. But to explain away constant poor results with "well, what can you expect with our catchment?" and then blaming motivated parents for rejecting such schools isn't acceptable. Well, not to me anyway.
All kids should have the right to a decent education, not just the ones whose parents can buy houses in the best school catchments.