Personally I think it is rude the lady said that, and as said, its not my cup of tea, but each to their own.
I woudl like to comment on some interesting points though and some personal opinion.
For me, I do too wonder for whom's benefit it is for and in my opinion, maybe its more for the mothers, and an aspect of not wanting their baby to have their own independence, letting go, etc. but thats just my psychology training coming in..
Also with regards to the sexual comments with boobs, my breast feeding book mentioned that it is common to get slightly aroused when breast feeding your baby, and so the fine line between them being 'sexual' or not is not that defined.
Finally, with the comment people make on other cultures, we are not living in those cultures, just as they are not living here. Maybe they would like to try our way, and might prefer it? We have a much more conveient, busy, working world,(in the West) where talking a baby into a client board meeting in a sling is not deemed appropriate, but thats our culture. Its the way we are. the fact that many do not extend breastfeed, is not a sad reflection on our society, its our culture. We dont not need to learn from other cultures, as many ways would not fit.
I have read the thread!
You say that you wonder whose benefit it is for, then your next point goes on to add that mum might get slightly aroused. That suggests that mum does it for her own benefit as it arouses her.
Surely you can see why I got confused there!