A thought experiment for breastfeeding mums out there: If strong scientific evidence was discovered showing that formula was the best thing for your baby, would you stop breastfeeding? (I wouldn't.)
I don't think bottlefeeding, or breastfeeding, is a logical decision. I didn't weigh up the evidence and decide to breastfeed, I knew I wanted to. Why? Probably because I'd always been told it was best. A friend I had in my 20s breastfed her daughter until she was 2.5y. I just figured it was the normal thing.
Nobody is saying "I know breast is best, and I know I could do it easily, but I've decided to bottlefeed out of sheer evillness." Some people aren't comfortable with the idea of breastfeeding. Many more people wanted to breastfeed, and didn't succeed. Everyone tries to do what they believe to be best for their babies and themselves.
I suspect that people who decided that breastfeeding just wasn't for them, weren't exposed to a lot of breastfeeding before they had their baby, or weren't exposed to positive stories of breastfeeding.
I suspect that a lot of people had problems partly because breastfeeding isn't normal in our culture. If we see our toddler walking in a way that isn't "right", we know right away. We all know what walking is supposed to look like, in toddlers and adults. But most of us don't know what breastfeeding is supposed to look like, because we never really see it. And if we do see it, we don't really look, because, eww, boobs.
All of which makes me realise that the more people breastfeed, particularly in public, the better. If breastfeeding is seen as being a perfectly normal thing to do, more people will be inclined to try it, or at least consider it.