Aye, why get a mini zebu for milk when you can get a pair of goats for a lot less? My goats (with the exception of the newest who has not yet figured out I am the giver of treats and affection) act just like dogs with hooves!
Some folks like the taste of cow milk over goat milk, or they just prefer working with cows more than goats. It could also be a matter of having allergies to goats and/or goat milk.