It's also common for attitudes to change very slowly with respect to something that has been around forever, that is available everywhere, and that can be safely used in moderation. It may be hard to accept that 'sugar addiction' is not an exaggeration; sugar brings to mind Valentine's Day, Halloween, and mom's apple pie, while addiction is associated with laying in the street, fatal overdoses, and ruined lives.
I certainly don't mean to say that everyone who likes sweets is automatically addicted to sugar. I use the term 'addiction' not to throw it around lightly, but because it is being used with its literal meaning by the medical professionals conducting said research, and because the usage is supported by the evidence (as can be seen in the links provided). That sugar addiction is being felt much less intensely than addictions to hard drugs, or that it can be overcome more easily, doesn't mean it doesn't fit the definition. Moreover, at a societal level, its consequences are just as dire (arguably, more so).