I hate to drag out the subject of the unmitigated cruelty some of us exhibit in keeping conjoined twins from sitting together, but there is a big difference between me not seeing a difference in two seat choices, and you not seeing why I see a difference.
There might be lots of reasons I wouldn't take 2C instead of 2B. Maybe my left shoulder is bad and I hate having it bumped when it is exposed to the aisle. Maybe I happen to know the person in 2D smells. Maybe lots of things. The point is, whether a seat is an even trade for my own seat is my call. Not your call to decide that it's just as good, and that I'm cruel if I don't see it your way.
This is a seat on an airplane. It does not say anything about anyone's humanity if they do or don't take a swap.