Count me on the "If they do it quite discreetly and modestly, then I see no problem" side.
I'm not too keen on someone being confrontational about it, or lobbing grenades on the issue.
I think on the Scriptural side of things: We should submit to one another out of reverence to Christ. And if church leadership sets down a policy--of course there should be room to talk, but there's an authority issue to consider.
Likewise, those in authority should be careful in exerting such. Being heavy-handed, rude, or the like does not honor God and does not edify the body.
Of course, it's easy to make the hard "always" and "never" statements here. I would hope that in "real life," each of us would respond carefully, gently, wisely...speaking the truth in love.
I will make one harsh statement: I feel it is NEVER right for fathers to breastfeed in church. That quickly becomes a sore subject.