"There shouldn't be a need for them at controlled pedestrian crossings. "
In theory, yes.
However in practice...
The crossing opposite my children's primary school has a very brief pedestrian phase. I wrote to the council asking them to lengthen it, as not only are school children trying to cross but there's old folk's sheltered housing adjacent too. Apparently that can't be done due to bus priority: the flip side of being on a main bus route.
Also, every day I witness drivers "just nip through" the lights following a column of traffic, who then get stranded at the junction by the red light, either just before the pedestrian crossing, or even straddling it. The majority of these drivers then try to 'sneak' through the second red light when traffic ahead moves off (as the next set of lights change), sometimes regardless of pedestrians trying to cross. It's a ridiculous and potentially dangerous behaviour.
So, lollipop ladies/men definitely required on this crossing!