I think Ryanair's rationale is that there aren't enough people (daft enough) to buy allocated seating so that revenue stream isn't performing - and some toxic little grey-faced gnome in the accounts department has had a brainwave - to make pax's lives so utterly miserable and fearful by threatening to subject them to lengthy, uncomfortable and hated queues at checkin with the added incentive of worrying if you're going to miss the flight (which is of course also to Ryanair's great financial advantage) thus inducing/co-ercing/bullying/frightening pax into coughing up for the outrageous allocated seating. $$Ker-ching$$
It also shows up the nasty cynical ripoff of charging £20 for an airport-provided boarding pass (perhaps because you've comitted the social crime of not posessing a smartphone) - when this new policy sees them dishing the damn things out en masse for free - so what was the justificaton of the £20 charge, except cynical opportunistic ripoff?
Having originally set off ostensibly trying to make air travel easier and more accessible they have now realised that by means of a total volte-face and turning it nasty and awkward they can extract yet more cash form their long-suffering victims.
What a revolting commercial morality these people have.