It's been the same for ages. I don't know if it's More London between City Hall and Tower Bridge. More London seems to tend their area very well, but who cares? Even if there is some fascinating bureaucratic excuse, it's the Mayor's job to get it fixed. He can see it from his window after all.
Yes. It's impressive how tourists try to compensate for British indifference to the settings of our own symbols. Maybe the answer is to pay the Tower Bridge beggars to clean the place up at weekends. This evening the bins and piles of garbage by the river had been cleared, but not the identical bins in Potters Field.