I don't have any specific critisism of Rosling (He seems very capable in a lot of ways). I think the part that many people find problematic is that he doesnt just present himself as a scientist but as someone who can interpret the data. And not just a normal interpreter but someone who has insights that almost nobody else has. You can argue wether this is true, but the fact is that this gives him an insane amount of credibility, and a kind of power that a non-expert should maybe use a little more sparingly.