Conditioning

My cats appear to eat directly from the food bowl & only from it.

One particular day, the bowl was wet so the kibbles were spread on the floor instead & the food was hardly touched. 

Why do they behave that way?

It could be a form of conditioning, that food is served in the food bowl

OR

Are cats aware of hygiene & they do not want to eat from the floor?

OR

A more existential question: Is it demeaning for the cats to eat off the floor? (Why are you treating me this way?)