Benefit changes

In their infinite wisdom?   our government has made certain changes to the benefits system here. 
Some I find difficult to get my head around.  Like the friend I have who suffers from Arachnoiditis, and has had his Disability Living Allowance taken away from him.  Even though he could become paralysed with no warning at all.
Many people are complaining about the so called "bedroom tax". 
I did wonder exactly what the "bedroom tax" was, so I looked it up.  Basically the government are saying that people existing on benefits can not expect everyone in their household to have a separate bedroom.
Now from an in all fairness viewpoint.  Why should families on benefits, and not working, have the luxury of separate bedrooms for everyone in the household?
My Dad worked right up until his early retirement, paid his taxes etc.  Didn't claim any benefits at all.  My sister and I shared a bedroom right up until my sister got married. We would have loved a room each, but Dad didn't earn enough.
I'm sure there are families where both parents work...or in the case of single parents....the parent works, and work very hard, but can only afford to have shared bedrooms for their children.  So why should they subsidise people who don't work?
Although the bedroom tax seems harsh, it only applies to people who are on housing benefit...in other words...the state puts a roof over their head...so why should they have better than the lower paid hard working people who claim no housing benefit?
And what prompted my deep thinking about this subject? 
I have a niece who has not worked since she left school pregnant at 16.  She has three children, one of which is disabled in some way....yet she has a roof over head  paid for by the state...a mobility vehicle, again, paid for by the state, she has a much better standard of living than I have, yet she is  dissatisfied with life.....
She hasn't spoken to me for 8 years because I wouldn't take time off  from a job I had just started....in order to look after her middle child., but that is another story.  I'm not jealous of her in any way, but can see exactly what the government are trying to achieve in her case.