That doesn't mean that the job is one that is actually needed
All jobs are needed, what ever they might be. The fact is though that over a very long period less labour power is required in the private sector. This isn't new. This has been happening over a very long period of time.
A good way to explain why jobs are needed for economic growth and sustainability, regardless of who pays the wages is to think about the news today.
Debt to GDP ration has risen by 4% this year. This is because of the cuts. What it illustrates is that our debt is rising because tax receipts are falling, unemployment and welfare needs growing and output falling. All jobs create output and tax receipts.