Agreed that not having pre-allocated seating is an issue.
But I've found that it can work in your favour too:- Of my 8 J* flights, I have been able to get exit row seating on all of them. The method is to check-in reasonably early to get in the first 'regular' boarding group.
So far, on all 8 flights, the passengers filled the plane starting from the front rows. No one (except for me) seemed to care about exit rows. Even with 30 persons in front of me, the exit rows have always been empty by the time I got to them. It's given me 8 reasonably pleasant flights.