Labeling consumer products "vegan" is problematic in terms of the vegan ideal. I'm not opposed to labeling products, but I do think it is preferable if such products where simply labeled "animal-free." This would be more accurate since the commercial and marketing use of the term "vegan" is only denoting that the product was produced or manufactured without using animal-derived ingredients or animal testing.
A company producing "vegan" labeled products is not claiming, and can't generally claim, that the products they are marketing are manufactured on the basis of vegan principles or beliefs. Unless one is referring to such principles or beliefs I think it is a mistake to use "vegan" as an adjective.
This applies equally to the use of the label "vegan" diet. The diet vegans follow is a vegetarian diet. That is, a diet consisting of vegetable-based foods to the exclusion of foods derived from animals. (Note that "lacto-" or "ovo-" are affixed to less than total vegetarian diets that include dairy or eggs respectively.) Of Course, vegans practice a vegetarian diet because of vegan beliefs and principles. But not everyone who consumes a totally vegetarian diet is doing so because of vegan principles or beliefs, so it is incorrect to label the diet "vegan."
Careless use of the term "vegan" as a general label for anything that excludes nonhuman animals can erode the moral, social, and political meaning of veganism. The result removes the vegan ideal from veganism itself. What we'll be left with as a result of this carelessness is veganism being replaced by a diet or more general consumptive pattern that is increasingly self-interested and individualized.
Veganism was founded as a movement for social change. In order to continue as a movement towards that aim we need to resist the temptation to reduce "vegan" to a mere consumer label.