Cuz...like they're not completely different....they kinda have the same taste..i guess this compensates for that fact that i dont like to drink normal milk without anything with it, but i love to drink chocolate milk, and i love eating vanilla ice cream, but i dont like chocolate ice cream. Also, isnt a milkshake just melted ice cream? I remember the days when i was just a lass and my mom brought me a milkshake from burger king, I but it in the freezer and when it froze, it pretty much became ice cream...just in a cup.