Campfire's target audience is the older child and its illustrations are intended for that audience. These are not visions of sugar plums. Ghosts are meant to be frightening. Poverty is ugly and depressing. People, even nice people, are not always pleasing to the eye.
In A Christmas Carol, as in his other novels, Dickens describes a world that is often not very pleasing. Think of Fagin and Sarah Gamp; think of Jo, the crossing sweep and the London fog in Bleak House.
If things turn out well as they often do, and indeed they do in A Christmas Carol, it does not alter the fact that the world can be an evil and frightening place, and Naresh Kumar's illustrations reflect that world quite effectively. While Dickens, even in spite of his attention to the horrors of the world he lived in, has often been accused of sentimentality, I would doubt that anyone would accuse Kumar's illustrations of anything even close.