Most Ryanair passengers don't actually check in at the airport. Many travel with minimal handluggage and proceed directly to security. Those who don't generally need only a baggage drop facility. So a vast space should not be required for this.
As for moving T3 security procedures and check-in to the vacated T1 space ... yes please! This would allow for considerable currently-occupied T3 floor space to be repurposed for expansion of airside facilities. That is sorely needed, and the sooner it can happen the better. I hope that the Pier B gates are annexed to T3 as well, allowing breathing room for Ryanair Group expansion. Their potential growth is strangled in T3 as it is currently formatted.
As for moving T3 security procedures and check-in to the vacated T1 space ... yes please! This would allow for considerable currently-occupied T3 floor space to be repurposed for expansion of airside facilities. That is sorely needed, and the sooner it can happen the better. I hope that the Pier B gates are annexed to T3 as well, allowing breathing room for Ryanair Group expansion. Their potential growth is strangled in T3 as it is currently formatted.