Priority boarding (after children and disabled) is already available to those with cabin-baggage only who check-in on-line with Ryanair - no extra cost. The A4 print-out boarding pass carries full details (including passport number) and has a scannable barcode.
It also has a boarding sequence number, which is not strictly adhered to, but you do get on after the kids.
I think it's to persuade more people to travel with only cabin baggage - makes it much easier. Last Sunday our Ryanair plane was delayed for an hour because two pax had not made the plane (due to understaffing at Stansted and chaotic arrangements), but their hold baggage had, necessitating offloading of their baggage. If I were MOL, under the present daft security rules, i would be exceeding pissed-off.
