Just wondering, why not 11B or 11F?
Isn't it better then 12 or I'm missing something?
Personally when I fly I cannot handle the jandal sitting in any A-C seat, and prefer window seats, so "K" it always is, however second would be isle seat in the middle. So I will always pick any "K" seat left, even if that is 66K even if 13A is available. I just simply get off the flight in a different mind set if I am not on the right hand side of an aircraft. So maybe 12J is the same.
Also in Business, often the IFE is on the wall, at a higher height, than in the back of the seat in front, so not only higher, but also further away. Combined with the greater chance in your feet getting bumped if in an isle seat with anyone half asleep going to the WC, or trolly dolly combined with turbulence - I actually avoid front row seats, even for extra leg room in Y.
So my guess is they like isle seats, and like the right hand side of the aircraft and/or don't want to sit in the front row.
Also to address the original theme of the thread, I do choose window seats over isle.
1- I don't get crawled over for the WC and woken up 5 minutes after I finally got to sleep - cause that is my duty sitting in K. If someone is sleeping, I will try to jump/step over them aka walking on the arm rests which often works 80% of the time without walking them. A little difficult if you are on a 3 -3/4-3 configuration and you have your row full - but hey you wake them on your schedule, not theirs, and free to sleep as you please without being bothered when you want to.
2- I do mainly medium haul, 3-4 hour, trans-Tasman flights, where you can hold it for most flights - so isn't a big issue, and often the urge to go is just after meal time, not in the middle of the flight
3- In long haul, you have something to lean on and it isn't your neighbor.
However I have got over being precious about personal space in Y, and a few times when my neghbour has make contact while trying to sleep, I no longer pull back/away, creating that awkward lets both try to do that again without touching each other situation - but just go with the flow, lean back with like, relax and enjoy the flight.