I think it's fair to say Ryanair are taking safety shots with the majority of routes. Warsaw will probably always work with a combination of city break tourism and emigrants visiting family etc. Malta works from virtually any UK airport. I guess where they've taken a risk you may say it's running Porto over winter, and to some degree Beauvais which seems to have steady loads.
There certainly is some truth in the argument regarding the Northern Ireland market, it's not like say Stansted where Ryanair could fly to literally any random airfield in Europe and create a demand, sunshine and UK domestic works best for operators, it would be nice to see more capital cities across Europe on the board, not having the likes of Brussels, Copenhagen, Madrid etc seems a loss to me.