I don't get the criticism and ridicule over the OP's original post. OP had an experience on a plane and posted their thoughts on it. Like thousands of others before. I've favored the angles some OPs have taken in their anecdotes, and others, not so much. But it's never seemed that attacking someone for posting in the first place was the thing to do. I didn't think that was the mojo here. It's FlyerTalk, not the comment threads on ft.com (no offense, FlyerTalk). Some sub-forums here even have
dedicated threads for this stuff.
What I mean is, if you're expecting every new topic here to be worthy of a Ted Talk or Nobel Prize or at least "not waste your time" for reading it, I believe you're on the wrong site.
Anyway...
For me, there's no 'one size fits all' response to these requests. Once in paid F SEA/OGG, a guy asked me to switch with his (adult) daughter in PE so they could sit together. It was a hard 'No'. In retrospect, I wish I'd also suggested that he switch with whomever *she* was sitting beside so they could be together. (Predictably, he was such a toddler the rest of the flight.)
In another case, when about 9 of us random folks weren't upgraded to FC until minutes before our flight was about to board MKE/SEA, I noticed an obvious couple who weren't placed beside each other, and one of them seemed clinically anxious about it (I am sorry; I'm not trying to be a dolt; I just don't know the best term to use for what they seemed to be experiencing). I went up to them, asked if they were the folks who'd been put in 3A and 3F, and offered to switch my 3C with 3F. I could tell it was a consequential result for them, not just a chance to hold hands a bit more that day or something.
So I keep a polite 'No thank you' at the ready in case this happens to me, but also aim to give a quick evaluation of the dynamic at play before responding. </my2cents>