Can't disagree with you there. Not only will you refuse a like-for-like swap (aisle to aisle) but you get annoyed at a stranger making a like-for-like swap? Um, ok.
No, it was not an aisle-for-aisle swap. Though, as previously written, that would appear to be the case. I fly a LOT. I find ways that I can control to make the experience less stressful and enjoyable. There's a method to my madness. :-) I choose very specific seats depending upon the aircraft with a goal in mind of being strategically located with a view to the lavatories. I drink only water and tea (no alcohol) and lot of it, so I want to be at the ready. In the previous example, I purposely flew a day later because the seats I wanted on the original flight were unavailable. Ultimately, that delayed my arrival into the targeted city. That was my choice and had no impact on anyone else. In my opinion, switchers think only of their needs and while a switch/swap might seem like a small thing, for some frequent flyers, it's a pain. Some couples (and those with children) often want the single flyer to accommodate their needs without regard to anyone else. Certainly, on United, if individuals want to sit together, plan for it. I do. And, if the person and their significant other happen to upgrade and are unable to sit together, deal with it. It's only a flight. My travel companions and I never seat together on a flight. We like aisle seats and if they are five rows away from me, that's OK. We'll see each other at the destination.
To be clear: I'm fine with people
asking, but please, don't "pretend" you didn't know that wasn't your seat. Or, don't perch in the unassigned seat and assume your smile and good humor will get you the seat. Really annoying. :-)