i think some women cannot help how the feel about "needing" a daughter. i think it's nature at work, making them feel like they need a clone so to speak? i don't think it can be helped. but what women without a DD need to realise is that she may be totally, utterly, completely different from you.
i have a DD, she is 2, i love her more than life, but she is not how i expected my child to be/look etc.. she's boisterous, fearless, very untidy and looks like her daddy. i wouldn't change her for anything or anyone but lately i have started daydreaming about having a son who has my colouring and looks more like me and is a little gentleman. i think it's because i have a teenage half brother who looks like me, is polite, sweet, funny and also loves spending time with me, going for coffees with me and is actually my good friend!
my DP adores his mum, they are not friends (as in they don't go shopping together or for coffee) but he loves her to bits and is very protective of her. DP's brother is also very close to his mum (as is his girlfriend) they go for meals with her, go on trips with her etc.. i have also found that most of the men in my family are very close to their mums in adult life, my grandmother has 7 kids (1 male, 6 females) my uncle is the one closest to her, they are literally clones of eachother, peas in a pod, best friends, she has always played a major role in his kid's lives.
some of the MIL threads on here can be a bit scary, but i don't think that's the norm in real life. i think it's how you bring your kids up. if you are a very close family and create that deep bond while the kids are young, you are always going to be close until the day you die. the idea that sons "leave" their mother's simply isn't true. yes, they will probably get a wife who will come first (as would a daughter with a husband) but they will always be your son and you will always be their mother and will always need and want eachother. your son can have as many girlfriends/wives as he likes over the course of life but he'll only ever have one mother (same as daughter)