I'm with you OP. I think a lot of the issues between PIL and DIL or SIL comes from insecurities on both sides. PIL are going to worry about the child they have raised and love and the partner may feel insecure about the relationship about that their DH or DW has with their parents. They are going to see the responsibilities and the relationship from an outside point of view and because there will be differences in how each family do things and what is considered normal, there may be conflict and confusion.
My family is large and overbearing, everyone knows everyone's business and there will be 1001 comments and remarks about how you should dress, keep a house and raise your children. They will tell you this to your face and we often argue because we're all loud and outspoken. But no one is offended by you telling them where to go, or well this is the way I'm doing it, if it doesn't work I'll think about doing it your way. Disagreements are common but no one takes anything personally unless you are personally attacking them rather than the idea/advice/suggestion, but because we're so loud and often sarcastic newbies are scared to say no or that they disagree. And my family use this to wind people up.
We're also a family of huggers and a family that will even after a row hug and say how much you love each other. We're the family that takes an hour to say goodbye because you hug and kiss everyone before you leave, and if you don't want to hug or kiss anyone, you will big hugged and kissed instead
(obviously if your not ok with it they won't but if your just awkward about initiating it they'll do it for you).
We're a lot to deal with and as an outsider daunting/terrifying and I know one of my BIL still finds it so. Because his family don't like each other and never speak to one and other unless they want something.
And there are aspects of my family I don't like and probably wouldn't choose, as a whole I love it so much. I could call anyone in my family and say I need you and someone would turn up ASAP and keep me on the phone the entire way so I wasn't alone (I live four hours away) with no questions asked. If I'd had an argument with anyone in my family and anyone family or not tried to talk shit about me, the person I'd argued with would jump to my defence. Because we can call each other names and row, but that doesn't give anyone else the right to and even when we 'hate' each other, we love each other fiercely.
I know should I have a baby my mother would insist on at least being in waiting room, ideally in the room with me and while I have no idea if that is what I want. I wouldn't stop her. I'm her child and her reasoning is that the husband is there to worry about his baby, she is there to make sure HER baby is ok, the grandbaby comes second to her. And I have a lot of complex medical issues and having someone like her in my corner is amazing. I would have no issue with PIL waiting in the waiting room but I'm not sure if I'd want MIL in the room with me as I don't have one but if I had a good relationship with her I'd consider it, but I would wonder WHY she'd want to watch that.
I also know that because of how my family is I'd struggle with adapting and acclimatising to how my DP's family works as a unit, because I am aware my family is atypical for most families to be judged against, but I'd do my best to fit into how they work in their home just as I'd expect DP to fit into my family at theirs. Between the two of us I'd expect us to take the bits we like best from both and merge them into one. I am also aware and understand that if I get with the guy I've a complicated relationship with that I'd do more to get him to speak to his parents because he doesn't like communicating without a point to the conversation whereas I talk to my mum and my siblings and their everyday, even if it's just a message to tell them that I love them. I know he loves his parents and when I asked how often he tells them that he told me, maybe I tell my mum once every 4-6 month depending if I've needed to talk to her, my dad birthdays and Christmas, and the same with his siblings who he says he never says it to, but he signs their cards that way. I know there is no underlying relationship issues here other than him being so bloody british and his 'pragmatic' I'll only message or call if I need to.
I don't understand how some people can hate their PIL's with such a passion when you love the person they created and raised. It's all about compromise and understanding each other as individual people and how their families work as a unit, and where you fit into that. If your unsure as to what your role is insecurities and hostility builds up making the entire thing more difficult than it needs to be.