Because pumping can take forever and once milk is pumped it’s in danger of spoiling. You have to keep it cold after pumping. Plus, you’re going to be making more milk and for women with high milk production, it gets mighty uncomfortable having all that milk in your boobs— imagine the feeling of really having to pee bad, but in your chest. Plus a lot of breastfed babies don’t like bottles. If you bottle feed or formula feed, that is totally cool. I support all moms’ feeding choices. But for breastfeeders, simply breastfeeding is easier!