It all comes down to publicity nothing more. I remember a few years back (1996-997) while in Toronto, a group of women had a legal fight for years with the Ontario government to allow women to go topless in public. Their argument was since men could walk on the streets without shirts on. And they can swim topless, they attend sporting events topless then women should have the same right.
Anyway, after years of discussions in the court, media and public a law was passed to allow women to go topless. Lots of men at that time applauded the decision since they don't have to go to strip clubs anymore to see some half naked women. But guess how many incidents of topless women walking on the streets or in sporting events or or or.... 2 cases the day the law was passed one of them was a landlord in a small building picked up the rent topless and the other a group of stripers sat outside a strip club topless and that does not count since they hardly ever have a cloth on.
The point is, ask all those women who defend breastfeeding in public how many of them will actually do it.???
Finally, in one episode of "Married with Children" a group of women protest against Al Bundy(one of my heroes) for not allowing a woman to breastfeed in his store. They said breastfeeding is natural and he replied so is peeing but you don't see me doing it in public.
Now I don't agree with the comparison but there are lots of things that are consider it natural but cannot be done in public.
As most suggested a child should be fed when hungry but put a scarf or something to cover it.
As for the men, I think they are against it out of jealousy. Because, they would love to see a woman barring it all but they prefer to be at the end of it not a small child.