I will never be tired of this phrase. Standing up for yourself and your household rules is hardly "childish and selfish". I would apply those pejoratives to people who think it's okay to disrespect others and abuse their hospitality.
As far as family goes, the OP is apparently fortunate not to have toxic relatives or family members who take advantage of them. A genetic link does not mean that a person has the right to be rude or abusive to another.
I am lucky, bravewolf, but my family, while not toxic, is definitely not perfect. We do all adore eachother, but we're in each others business constantly. I just cannot even fathom my mom or my sister wanting me to come down for dinner on Friday, me not wanting to, and simply saying "I'm afraid that won't be possible." That wouldn't fly for even one second. I'd literally have to say it, hand up the phone that very same second, and be prepared to screen my calls all night. Annoying, yes. Toxic, no.
I've been pondering this thread a lot laterly, and it occurs to me that first, there are different ways to say it, but second, there are actually kinder, smoother ways to say the same thing in situations where the person asking isn't really crossing some big line, or being toxic, or being too insistent, etc, but you still aren't interested in really giving a detailed explanation.
Like in your example, auntmeegs - let's assume you couldn't go to dinner for some reason you didn't want to tell your sister - but she's not out of line for inviting you to dinner, so you don't want to make her feel bad, or give her a verbal cut (which is sometimes how IATWBP comes out) - you could say "Aww gee, that sounds so nice. Wish I could, but I just don't think I'm going to be able to make it tonight..."
But then again, sis is probably still going to want to know why...
I take your point though, auntmeegs - which, if I'm reading it right is that there are situations where the phrase is cruel and unwarranted. If my mother called and said she'd like to come visit me in May, and I said "I'm afraid that won't be possible" and just kept repeating it, she'd think I'd lost my mind, then she'd slowly decide I hated her, and our rel
ationship would deteriorate. But that's because in our rel
ationship, calling and saying "I'm coming in May, what weekend is good for you?" is generally met with me going "Yay!! Any weekend... all of them!". So it would be bizarre and cruel for me to say IATWBP. But if I said "Aww, gee mom, May really sucks for me - what about June?" it wouldn't be a problem.
Or if my best friend called me sobbing, saying that her fiance had just walked out on her and could I please please come over - to say IATWBP would be insane, and terribly cruel. I think that situation warrants an explanation for why I can't come to my friend in her hour of need. But if I had a toxic friend (an old college buddy comes to mind) who did this every other Tuesday, I might use the phrase and not be bothered by it.
I think I've started rambling. But I stand by the idea that
misplaced, the phrase can be cruel.