It's not their own home though, is it? They're social homes, for people who need them the most. And when they're sold off, they don't get replaced because local authority budgets are slashed and councils are prevented from borrowing money to replace them (scheduled to change, thankfully). It's a nasty, nasty backdoor policy which is one of the reasons why we've seen a proliferation of people living on the streets. By the same token, do you think governments should force all landlords to sell their homes?
The most woeful record of council house building was under the Blair/Brown governments. It was oft stated, but entirely true that the Thatcher government in its worst year built more than twice as many houses in a year as Labour did in their entire 13 years in office.