Quite simple really, the rates should not have gone down in the first place.Instead of people paying down their mortgages etc, they have just bought more, bigger houses etc etc and the slightest move upward, sh... will happen.
Effectively or to a degree, the self funded retirees who had invested their money in Banks, are effectively paying for these wants of many people, with the disgusting rates they now get on their money.
It's a bit like Rats chewing on your hard earned money, it's vanishing.