A problem with a lot of the solutions that require adding insulation to walls or floors means a disruption to the people living there, generally needing them to move out for a time if you need to do the work inside the property. Adding it to the ceiling is the least efficient but also the least disruptive.
Would be good if they are adding an insulation layer as well, though if they are doing this as a research project they may well want to do a few different combinations to see what works.
Housing Associations and council housing was screwed over by Thatcher and subsequent governments have never been willing to do more than token changes, so any fixes are going to be minimum cost and not the best long term solutions.
