But that is an assumption that a child will be manipulative if given perceived 'free rein' or preference in any way.
Not in any way, but someone up thread suggested that they were shocked people view their children as manipulative. My point was that childhood is the time when people learn all manner of negative traits, including manipulation. So yes, being manipulative, being selfish etc, are common phases for children to go through as they develop and it isn't insulting to them to acknowledge that on here.
A lot of good parenting is about being a bit uncomfortable oneself in order to meet a child's needs... If a child's needs for space/resources would suggest giving them a bigger room is the right thing to do, why ever would you not
A lot of good parenting is also about teaching children the difference between wants and needs. I feel like I made it clear in my last comment that if there were obvious practical reasons why only this way made sense - such as the small room was unsafe, or there literally wasn't enough room for his things and there would have been for mine, then I wouldn't stick to the rule. But if the room is big enough for his things and is perfectly adequate, he just wants a bigger one, then I wouldn't switch. I also personally believe that the amount of sacrifices you should have to make for your children's whims should go down as they get older and develop empathy. So I don't think giving up your bedroom for a six year old that is fine in his is in the same league as waking up during the night with a baby, like you said in your post.
just to maintain some kind of sense of being the 'head of the house' (or the 'one who's paying' - I do sort of understand that, and I have said to my dc in relation to specific things that as long as I'm the one who would be paying for it it isn't going to happen, but I think a general, abstract message that economic might is right is not one I want to teach)? I pull rank with my dc when I need to, but I don't feel the need to have that permeate the entire way we live together.
I don't know what you want me to say here. Within reason, I do think the parent needs to be head of he house. I don't think it's about economic might, the only reason money comes into it is because they need to learn that if somebody else has paid for something, then it is theirs to make decisions about. Otherwise a) they may not respect other people's property or be grateful when people buy them things, because they view money as communal, and b) why would they ever see the appeal of moving out and becoming independent, when they get to make all the decisions at mum's house and she pays for it?
But the main reason the parent is the head of the house, is simply because they are the responsible adult, and I want my kids to know there are pitfalls and perks to that. So you don't get to go to many cool birthday parties and you have to go to work, but you get to run your own household and decide what you want to do for yourself, set your own bedtime etc, which is not an option for a child. Also, adults get to have grown up relationships, which is another reason I associated double bedrooms with adults as a child and wouldn't switch to a box room if I were OP, as it sets the precedent that this is never going to happen for his sake. Also, I was raised to respect an adults comfort because their bodies are older and capable of less - so if there weren't enough seats the children have to sit on the floor. Likewise, it is less practical for an adult to be in a box room because they don't fit in a single bed as well as a child and are too old to comfortably get up and down from a bunk bed.
That balance of perks and pitfalls taught me to simultaneously respect my parents authority, enjoy the lack of responsibilities of childhood, and actually look forward to being an adult, rather than just thinking becoming an adult meant a never ending cycle of adults sacrificing themselves for children. There's no reason why what I'm describing needs to permeate the house, I'm trying to articulate something that I think for most of us is very normal. It would never occur to me to think I was going to get the master bedroom while my parents were in bunk beds in a box room, because I just understood that they were the adults and I was the child, and one day I would get the master bedroom (and I'd probably spend a while fantasizing about how I would decorate it, and then put it out of my mind). I was a happy and secure child, and I believe this was largely due to the fact that I didn't think absolutely everything was up for negotiagion and face disappointment if my parents said no. It's something I see a lot in children and am keen to avoid.