The "legal minimum" is not an unsafe amount. A margin for error is built in. Michael O'Leary has repeatedly been quoted as saying that their own requirements exceed the legal minimum, and pilots have discretion to load additional fuel on top of that. With only 3 fuel incidents, all on the same day, all in the same area, due to severe weather in the area, and these being the only fuel incidents across more than a half-million flights, I don't think that there is any endemic safety issue. Ryanair is the airline regulatory agencies love to hate; if they were doing anything unsafely, I think they'd be called on the carpet quickly.