In some instances of course they are demonstrations of cultural imperialism - the China to Chinatown book suggests that the creation of Chinese-American food like chop suey was to make people like Chinese food better, and therefore like Chinese people better.

Yes, and I should have mentioned that too *edits*.

Did you read the comments? There's all these people saying "Well, it's chinese people's fault for selling that sort of food!". With the implication that if they'd just stuck to "authentic" dishes when they came over americans would have cheerfully acclimatised, or at worst shrugged their shoulders and gone "Oh well, different strokes I guess".

EDUT: Oh and with fusion food for me at least the problem is the implication (as with so much cultural appropriation) that the bastardised version is "inventive" and "hip" in a way the original isn't.