The answer is "because it has no emotion and doesn't deal with complex motivation".
Cognitive psychology is a term which was first utilized in 1967 by Ulric Neisser in his book Cognitive Psychology. As indicated by Neisser, cognition includes "all procedures by which the tactile info is changed, lessened, expounded, put away, recouped, and utilized." Neisser likewise recommended that given such a wide and clearing definition, insight was associated with everything without exception that individuals do.