I'm a guy, I don't like big breast... I prefer flat or just small... It feels like saying stuff like this it could get me crucified, ahah. (but I am sure I am most definitely not alone)
It's all just a matter of preference. I think it's mainly people taking offense from others going out of their way to post "I don't like x because I prefer y" on something they shouldn't really need to comment on, which I think is the fault of both parties for getting worked up at. Just ignore things you don't prefer (that's why there's tags) and ignore people that dislike what you prefer, etc.
Personally I have no preference to breast size in reality or with things like manga, especially since I translate things like this as well as things like softcharm which is flat as a board loli smut.