this is the automatic no, i don't care if your seat is next to a braless hottie on an ice cold plane
I don't usually switch except for an even exchange. I find it is usually the wife and not the husband whose asking me to change. I had one suggested switch from an aisle F to bulkhead F. As I'm 6'2" and have had a few knee injuries/surgeries, stretching out is something I value, and have turned down the proposed switches that reduce leg room. I do always propose that they consider switching with the person in the other row. That has never happened. Not sure why. When I haven't switched, I sometimes get grumping from the unhappy wife, though in one case (BOS-MIA), I had a lovely conversation with the wife even though I didn't take the bulkhead F. I prefer to be generous when I can.
I am just not going to let people's sense of entitlement or grumping bother me. Life is too short.
Interestingly, there do seem to be two sets of attitudes about asking. I have a sister-in-law who is very self-focused. She wants to make things just so for herself and family. She will make requests that I find insensitive but she figures, "You might not mind, so there's no harm in asking." However, if you say to her the magic new age code words, "That doesn't work for me," she completely backs down and takes no offense. And, if you communicate your needs to her, she tries to include that in her definition of "just so."
I on the other hand wouldn't ask if I thought the request was unreasonable or unfair. Not so with SIL. I've just learned to let it go (sometimes I have a response and then let it go). Interestingly, she is a bit sensitive on the couple of occasions when I decided to assert what I want (when with others I would have coordinated more delicately).