Who said anything about charity? Ryaniar must be happy with the yields as they are continuing the flights and as these are non based flights those bases may not have the aircraft to operate extra flights or may feel that for the market the current flights are enough and that additional flights might then effect their yield.
As for Ryanair not adding new routes or not basing only Ryanair knows and maybe the airport knows the reason personally I'd love to ask MOL but I doubt he'd tell a non expert like me! They do seem to be concentrating on expanding in Germany at the moment so I'd suggest that is where their focus is and CWL is small fry compared to that.
In the end it is Ryaniars choice whether they believe CWL will make them money. Personally I think it would but again that is my personal opinion based on the evidence that I've seen and if you look at the historical numbers for what CWL used to sustain in the past that would also suggest more flights even if they were seasonal would be sustainable for airline like Ryanair.