Are you sure? I feel like it's the opposite. Nearly everyone I've flown with in the last few months has let me pick a seat in advance. I can even pay for the premium seats in advance.
What's new is that Ryanair used to not have any assigned seats. You got onto the plane and picked a free seat. It's a good way to ensure passengers get on quickly, so that the plane can take off 25 minutes later. Wonder what the assigned seating is doing to their turnaround times.
Everyone does that now. Delta, BA, AA, Virgin, etc. I can think of very few airlines that give you free seat selection before check-in.
I don't agree with it, but it is the way things have gone for all airlines. Just like baggage fees on local flights (even though that causes mass delays during boarding since now everyone is trying to show too much into cramp overhead lockers).