Awww its a shame that some people are negative about BFing. I've gotten nothing but encoragement for BFing, everytime I tell anyone I BF exclusively I just about get a gold pin! It's mae me feel really supported and validated. But if I did get negativity it would probably make me feel like needling them a bit about bottle feeding lol! I'm so immature!
What I do get a bit of negativity on is the fact that I refuse to let my baby "cry it out", a lot of mums imply that I'm spoiling her by rocking her to sleep, going to her when she cries etc and like you said it's probably because they feel guilty and defensive about letting their babies cry. I'm sure no mother would willingly let their baby cry. It's usually when they're at their wit's end and sleep deprived and probably have to get to work the next day! Whatever the case is, no one should shove their opinions down other people's throats. People are generally diplomatic with other issues like religion, politics, vegetarianism etc but with pregnancy and childcare, everyone's an expert it seems!