In fact, I prefer the middle seat.
The middle seat.
And I've been wedged in there with some fat people. And I'm a little tubby now, but I've been fat myself.
Still, I prefer the middle seat to the aisle. Of course, the window is best.
But the middle protects me from passersby. The middle protects me from the cart.
If we are dealing with a row of three seats (A,B,C), the aisle seat also has to deal with double the number of requests to give way to those needing to go to the bathroom (A and B instead of just A).
Furthermore, if you want to use the "I like to get up whenever I want thus you like the window seat" argument; if you are a B seat all you have to do is wait until the C seat goes to the bathroom and you are home free, no unneeded social interaction, at all. This is unlike an A seat, where you have a high chance of only having to ask one person to yield to you, but a low probability of zero social interaction (i.e. two seats being concurrently unoccupied). The B seat does not know when this will occur, but it has a near certainty of some periods of zero required social interaction.
So, if you ask me, the middle seat is not all that bad.