I was wondering the same thing !!
And I also noticed that sometimes the exit row seats are the last to fill.
95% of the time i can get easily the exit row seat, usually at the airport.On OS you can't choose them for free when booking and they are blocked during OLCI..I even tell all my friends whenever they're flying - Exit row+free middle seat+do&co a la carte = intra european first class ..

The frequent flyers indeed prefer to sit in the front (such a waste when on remote stand lol ).
The non-frequent flyers just have no idea about the legroom. Once i even heard some folks in the exit row behind me saying something like ''oh my god , did u hear what the flight attendant said !? we have extra responsibility now , we should get payed to be sitting here ''