At the time of check-in, often weeks in advance with the lcc model, two seats together may not be available. Closer to departure, as the flight is managed, adjacent seats could become available, but by then it isn’t easy to reseat allready checked in passengers.
If I am booking close to departure, and am prepared to pay for seat selection, I certainly don’t want all the aisle/window seats to be allocated to people that haven’t paid.
Oh dear; you have allowed yourself to become brain washed. Is it the LoCo syndrome or just punch drunk?
In the beginning there was only free seating and a scrum at boarding time. Slowly, and for dubious reasons, seat allocation crept in; just like normal airlines. I suspect it was to speed up boarding and had nothing to do with pax convenience. Then LoCo's realised there might be some mileage/profit in charging for specific seating, i.e. front row & extra leg room overwings etc. Those who didn't want these were allocated seats at random, but together if on the same booking. Then has come the 'pay for any seat choice' system. To encourage that it is alleged that same booking pax are being separated.
If that is true it means that a group of marketing whallas have sat around a table; some one has thrown that idea into the hat, and they have agreed to implement yet another fleecing tactic. That must be true because it wasn't there 5 years ago, and it didn't invent itself. It just shows the mentality of Monday morning meetings. What will be the new 'fleece of the week'?