I'm a breastfeeding counsellor, swmum, though I also have an academic interest and experience in the science of attachment and early parenting.
I think, like you, that we should do what we think is best for our own families and for ourselves. This may mean deciding that for us, some of the research into babycare/child development/infant feeding is not applicable, or strong enough, or whatever, to change our preferences. OK by me!
As I say, breastfeeding responsively (I don't like 'demand' feeding as a phrase!) and co-sleeping enhances many health and developmental processes - read 'The Science of Parenting' by Margot Sutherland, or 'Why Love Matters' by Sue Gerhardt for a good explanation of the science behind what I am saying. You will not be able to find any good scientific literature which says anything different - the advances in biochemistry and neuro-science in the last 10-15 years have revealed, and explained, a lot. This has gone way beyond the differences of opinion you are are so keen on!
None of this means that someone who formula feeds and who does not co-sleep cannot be a 'good' parent, or that bf and co-sleeping is the only way to be a 'good' parent. Many good parents choose not to do this. But this does not remove the science about what enhances early physical and psychological health. This is not a 'sweeping' statement. It's based on evidence.
By the way, the evidence that parenting responsively in the way I am describing does not produce needy, insecure babies is well-established. In fact, the opposite is the case. Responding to your baby's needs by feeding when he cues (this does not have to be by breastfeeding, though it's easier to do it if you are), comforting at night (by sleeping close by, if not actually in the bed) without leaving the baby to cry, produces confident, secure babies who cry and whine less as older babies and toddlers.
I have references for this going back some 40-50 years right up to the present day - it really is a corner-stone of our understanding now - but I don't think you'd be interested in reading them.
To repeat - I don't judge parents for choosing other ways of parenting. This is not the only way to be a good parent. But I do ask you not to promote suggestions that it produces 'needy, insecure' babies...your own observations and experience do not trump the research into (now) thousands of outcomes. If these babies are needy and insecure, it is not because they have been bf for 9 months and co-slept....