Why do you have to start calling names ("snowflake"). No need for aggression.

And it is precisely about aggression.

How do I know that someone that asks "nicely" is going to also nicely accept the refusal? I bet 99% of the times there is a refusal the person asking will make a face, a passive aggressive comment, or go away mumbling something.
Some people don't like confrontation. The moment someone asks for a seat swap I am like "OH LORD, here it comes". Not rarely, it makes for an unpleasant interaction. OR retaliation (punching your seat back, for example)
There are other people that simply want to be on their headphones or book or whatever and absolutely do not want to talk to anybody. They are in their full right to do so unless it is a Flight Attendant.

Personally, I would ask the gate agent or flight attendant and not deal with asking any passenger. And If I have to fly separated from my husband or parent, then so be it.
Seating apart form a loved one is one of the risks of traveling. Managing that risk will not depend on the will of other pax, at least for me.