When Should You Switch Seats On A Plane?

Reader Abe emailed me an interesting question:

“Would you change seats if a husband wife duo requested you do so even if it inconvenienced you either by meal choice, or took away your aisle seat, and turned it into a widow in the back?”

I figured I’d answer it here, since I’m curious what you guys think.

With airlines holding back upgrade seats until the last minute nowadays, you see people trying to change seats all the time to sit with colleagues, loved ones, etc. So under what circumstances should you switch seats?