I don't really agree with this... My niece is turning two next week and she can pick batman out of any characters that you show her. She also has a powerwheels batmobile. (This could be because her dad is a Batman nut??) Plus, she has 2 or 3 batman Duplo sets.
Another example, my friends 3 year old came over and we were playing legos and she wanted to play with... Batman. She chose him over any other minifig I had including the Disney CMF set. A few weeks later she was still asking her mom if she could come to our house and play Batman.