We can sit here pricing up flight comparisons all day long. The same could be said if you compared flights from different Scottish or Irish Airports. The point trying to get through is CWL IS starting to be competitive with better value from FR, BE, VY and QR. Sometimes it'll work for some, sometimes it wont.
Many people have flown into 2nd rate airports for FR for years and now DY in the US because of price. Many flyers are price driven and won't worry about other factors.